diff -pruNX dontdiff c/CREDITS badram/CREDITS --- c/CREDITS 2005-06-30 21:03:55.000000000 +0200 +++ badram/CREDITS 2005-07-01 11:35:48.000000000 +0200 @@ -2758,6 +2758,15 @@ S: 6 Karen Drive S: Malvern, Pennsylvania 19355 S: USA +N: Rick van Rein +E: rick@vanrein.org +W: http://rick.vanrein.org/ +D: Memory, the BadRAM subsystem dealing with statically challanged RAM modules. +S: Binnenes 67 +S: 9407 CX Assen +S: The Netherlands +P: 1024D/89754606 CD46 B5F2 E876 A5EE 9A85 1735 1411 A9C2 8975 4606 + N: Stefan Reinauer E: stepan@linux.de W: http://www.freiburg.linux.de/~stepan/ diff -pruNX dontdiff c/Documentation/badram.txt badram/Documentation/badram.txt --- c/Documentation/badram.txt 1970-01-01 01:00:00.000000000 +0100 +++ badram/Documentation/badram.txt 2005-07-01 11:35:48.000000000 +0200 @@ -0,0 +1,266 @@ +INFORMATION ON USING BAD RAM MODULES +==================================== + +Introduction + RAM is getting smaller and smaller, and as a result, also more and more + vulnerable. This makes the manufacturing of hardware more expensive, + since an excessive amount of RAM chips must be discarded on account of + a single cell that is wrong. Similarly, static discharge may damage a + RAM module forever, which is usually remedied by replacing it + entirely. + + This is not necessary, as the BadRAM code shows: By informing the Linux + kernel which addresses in a RAM are damaged, the kernel simply avoids + ever allocating such addresses but makes all the rest available. + +Reasons for this feature + There are many reasons why this kernel feature is useful: + - Chip manufacture is resource intensive; waste less and sleep better + - It's another chance to promote Linux as "the flexible OS" + - Some laptops have their RAM soldered in... and then it fails! + - It's plain cool ;-) + +Running example + To run this project, I was given two DIMMs, 32 MB each. One, that we + shall use as a running example in this text, contained 512 faulty bits, + spread over 1/4 of the address range in a regular pattern. Some tricks + with a RAM tester and a few binary calculations were sufficient to + write these faults down in 2 longword numbers. + + The kernel recognised the correct number of pages with faults and did + not give them out for allocation. The allocation routines could + therefore progress as normally, without any adaption. + So, I gained 30 MB of DIMM which would otherwise have been thrown + away. After booting the kernel, the kernel behaved exactly as it + always had. + +Initial checks + If you experience RAM trouble, first read /usr/src/linux/memory.txt + and try out the mem=4M trick to see if at least some initial parts + of your RAM work well. The BadRAM routines halt the kernel in panic + if the reserved area of memory (containing kernel stuff) contains + a faulty address. + +Running a RAM checker + The memory checker is not built into the kernel, to avoid delays at + runtime. If you experience problems that may be caused by RAM, run + a good RAM checker, such as + http://reality.sgi.com/cbrady_denver/memtest86 + The output of a RAM checker provides addresses that went wrong. In + the 32 MB chip with 512 faulty bits mentioned above, the errors were + found in the 8MB-16MB range (the DIMM was in slot #0) at addresses + xxx42f4 + xxx62f4 + xxxc2f4 + xxxe2f4 + and the error was a "sticky 1 bit", a memory bit that stayed "1" no + matter what was written to it. The regularity of this pattern + suggests the death of a buffer at the output stages of a row on one of + the chips. I expect such regularity to be commonplace. Finding this + regularity currently is human effort, but it should not be hard to + alter a RAM checker to capture it in some sort of pattern, possibly + the BadRAM patterns described below. + + By the way, if you manage to get hold of memtest86 version 2.3 or + beyond, you can configure the printing mode to produce BadRAM patterns, + which find out exactly what you must enter on the LILO: commandline, + except that you shouldn't mention the added spacing. That means that + you can skip the following step, which saves you a *lot* of work. + + Also by the way, if your machine has the ISA memory gap in the 15M-16M + range unstoppable, Linux can get in trouble. One way of handling that + situation is by specifying the total memory size to Linux with a boot + parameter mem=... and then to tell it to treat the 15M-16M range as + faulty with an additional boot parameter, for instance: + mem=24M badram=0x00f00000,0xfff00000 + if you installed 24MB of RAM in total. + +Capturing errors in a pattern + Instead of manually providing all 512 errors to the kernel, it's nicer + to generate a pattern. Since the regularity is based on address decoding + software, which generally takes certain bits into account and ignores + others, we shall provide a faulty address F, together with a bit mask M + that specifies which bits must be equal to F. In C code, an address A + is faulty if and only if + (F & M) == (A & M) + or alternately (closer to a hardware implementation): + ~((F ^ A) & M) + In the example 32 MB chip, we had the faulty addresses in 8MB-16MB: + xxx42f4 ....0100.... + xxx62f4 ....0110.... + xxxc2f4 ....1100.... + xxxe2f4 ....1110.... + The second column represents the alternating hex digit in binary form. + Apperantly, the first and one-but last binary digit can be anything, + so the binary mask for that part is 0101. The mask for the part after + this is 0xfff, and the part before should select anything in the range + 8MB-16MB, or 0x00800000-0x01000000; this is done with a bitmask + 0xff80xxxx. Combining these partial masks, we get: + F=0x008042f4 M=0xff805fff + That covers everything for this DIMM; for more complicated failing + DIMMs, or for a combination of multiple failing DIMMs, it can be + necessary to set up a number of such F/M pairs. + +Rebooting Linux + Now that these patterns are known (and double-checked, the calculations + are highly error-prone... it would be neat to test them in the RAM + checker...) we simply restart Linux with these F/M pairs as a parameter. + If you normally boot as follows: + LILO: linux + you should now boot with + LILO: linux badram=0x008042f4,0xff805fff + or perhaps by mentioning more F/M pairs in an order F0,M0,F1,M1,... + When you provide an odd number of arguments to badram, the default mask + 0xffffffff (only one address matched) is applied to the pattern. + + Beware of the commandline length. At least up to LILO version 0.21, + the commandline is cut off after the 78th character; later versions + may go as far as the kernel goes, namely 255 characters. In no way is + it possible to enter more than 10 numbers to the badram boot option. + + When the kernel now boots, it should not give any trouble with RAM. + Mind you, this is under the assumption that the kernel and its data + storage do not overlap an erroneous part. If this happens, and the + kernel does not choke on it right away, it will stop with a panic. + You will need to provide a RAM where the initial, say 2MB, is faultless. + + Now look up your memory status with + dmesg | grep ^Memory: + which prints a single line with information like + Memory: 158524k/163840k available + (940k kernel code, + 412k reserved, + 1856k data, + 60k init, + 0k highmem, + 2048k BadRAM) + The latter entry, the badram, is 2048k to represent the loss of 2MB + of general purpose RAM due to the errors. Or, positively rephrased, + instead of throwing out 32MB as useless, you only throw out 2MB. + + If the system is stable (try compiling a few kernels, and do a few + finds in / or so) you may add the boot parameter to /etc/lilo.conf + as a line to _all_ the kernels that handle this trouble with a line + append="badram=0x008042f4,0xff805fff" + after which you run "lilo". + Warning: Don't experiment with these settings on your only boot image. + If the BadRAM overlays kernel code, data, init, or other reserved + memory, the kernel will halt in panic. Try settings on a test boot + image first, and if you get a panic you should change the order of + your DIMMs [which may involve buying a new one just to be able to + change the order]. + + You are allowed to enter any number of BadRAM patterns in all the + places documented in this file. They will all apply. It is even + possible to mention several BadRAM patterns in a single place. The + completion of an odd number of arguments with the default mask is + done separately for each badram=... option. + +Kernel Customisation + Some people prefer to enter their badram patterns in the kernel, and + this is also possible. In mm/page_alloc.c there is an array of unsigned + long integers into which the parameters can be entered, prefixed with + the number of integers (twice the number of patterns). The array is + named badram_custom and it will be added to the BadRAM list whenever an + option 'badram' is provided on the commandline when booting, either + with or without additional patterns. + + For the previous example, the code would become + + static unsigned long __initdata badram_custom[] = { + 2, // Number of longwords that follow, as F/M pairs + 0x008042f4L, 0xff805fffL, + }; + + Even on this place you may assume the default mask to be filled in + when you enter an odd number of longwords. Specify the number of + longwords to be 0 to avoid influence of this custom BadRAM list. + +BadRAM classification + This technique may start a lively market for "dead" RAM. It is important + to realise that some RAMs are more dead than others. So, instead of + just providing a RAM size, it is also important to know the BadRAM + class, which is defined as follows: + + A BadRAM class N means that at most 2^N bytes have a problem, + and that all problems with the RAMs are persistent: They + are predictable and always show up. + + The DIMM that serves as an example here was of class 9, since 512=2^9 + errors were found. Higher classes are worse, "correct" RAM is of class + -1 (or even less, at your choice). + Class N also means that the bitmask for your chip (if there's just one, + that is) counts N bits "0" and it means that (if no faults fall in the + same page) an amount of 2^N*PAGESIZE memory is lost, in the example on + an i386 architecture that would be 2^9*4k=2MB, which accounts for the + initial claim of 30MB RAM gained with this DIMM. + + Note that this scheme has deliberately been defined to be independent + of memory technology and of computer architecture. + +Known Bugs + LILO is known to cut off commandlines which are too long. For the + lilo-0.21 distribution, a commandline may not exceed 78 characters, + while actually, 255 would be possible [on i386, kernel 2.2.16]. + LILO does _not_ report too-long commandlines, but the error will + show up as either a panic at boot time, stating + panic: BadRAM page in initial area + or the dmesg line starting with Memory: will mention an unpredicted + number of kilobytes. (Note that the latter number only includes + errors in accessed memory.) + +Future Possibilities + It would be possible to use even more of the faulty RAMs by employing + them for slabs. The smaller allocation granularity of slabs makes it + possible to throw out just, say, 32 bytes surrounding an error. This + would mean that the example DIMM only looses 16kB instead of 2MB. + It might even be possible to allocate the slabs in such a way that, + where possible, the remaining bytes in a slab structure are allocated + around the error, reducing the RAM loss to 0 in the optimal situation! + + However, this yield is somewhat faked: It is possible to provide 512 + pages of 32-byte slabs, but it is not certain that anyone would use + that many 32-byte slabs at any time. + + A better solution might be to alter the page allocation for a slab to + have a preference for BadRAM pages, and given those a special treatment. + This way, the BadRAM would be spread over all the slabs, which seems + more likely to be a `true' pay-off. This would yield more overhead at + slab allocation time, but on the other hand, by the nature of slabs, + such allocations are made as rare as possible, so it might not matter + that much. I am uncertain where to go. + + Many suggestions have been made to insert a RAM checker at boot time; + since this would leave the time to do only very meager checking, it + is not a reasonable option; we already have a BIOS doing that in most + systems! + + It would be interesting to integrate this functionality with the + self-verifying nature of ECC RAM. These memories can even distinguish + between recorable and unrecoverable errors! Such memory has been + handled in older operating systems by `testing' once-failed memory + blocks for a while, by placing only (reloadable) program code in it. + Unfortunately, I possess no faulty ECC modules to work this out. + +Names and Places + The home page of this project is on + http://rick.vanrein.org/linux/badram + This page also links to Nico Schmoigl's experimental extensions to + this patch (with debugging and a few other fancy things). + + In case you have experiences with the BadRAM software which differ from + the test reportings on that site, I hope you will mail me with that + new information. + + The BadRAM project is an idea and implementation by + Rick van Rein + Binnenes 67 + 9407 CX Assen + The Netherlands + rick@vanrein.org + If you like it, a postcard would be much appreciated ;-) + + + Enjoy, + -Rick. + diff -pruNX dontdiff c/Documentation/kernel-parameters.txt badram/Documentation/kernel-parameters.txt --- c/Documentation/kernel-parameters.txt 2005-06-30 21:03:55.000000000 +0200 +++ badram/Documentation/kernel-parameters.txt 2005-07-01 11:35:48.000000000 +0200 @@ -26,6 +26,7 @@ restrictions referred to are that the re APIC APIC support is enabled. APM Advanced Power Management support is enabled. AX25 Appropriate AX.25 support is enabled. + BADRAM Support for faulty RAM chips is enabled. CD Appropriate CD support is enabled. DEVFS devfs support is enabled. DRM Direct Rendering Management support is enabled. @@ -256,6 +257,8 @@ running once the system is up. aztcd= [HW,CD] Aztech CD268 CDROM driver Format: ,0x79 (?) + badram= [BADRAM] Avoid allocating faulty RAM addresses. + baycom_epp= [HW,AX25] Format: , diff -pruNX dontdiff c/Documentation/memory.txt badram/Documentation/memory.txt --- c/Documentation/memory.txt 2004-12-24 22:35:49.000000000 +0100 +++ badram/Documentation/memory.txt 2005-07-01 11:35:48.000000000 +0200 @@ -18,6 +18,14 @@ systems. as you add more memory. Consider exchanging your motherboard. + 4) A static discharge or production fault causes a RAM module + to have (predictable) errors, usually meaning that certain + bits cannot be set or reset. Instead of throwing away your + RAM module, you may read /usr/src/linux/Documentation/badram.txt + to learn how to detect, locate and circuimvent such errors + in your RAM module. + + All of these problems can be addressed with the "mem=XXXM" boot option (where XXX is the size of RAM to use in megabytes). It can also tell Linux to use less memory than is actually installed. @@ -49,6 +57,8 @@ Try: Linux to using a very small amount of memory. Use "memmap="-option together with "mem=" on systems with PCI to avoid physical address space collisions. + If this helps, read Documentation/badram.txt to learn how to + find and circumvent memory errors. Other tricks: diff -pruNX dontdiff c/arch/i386/Kconfig badram/arch/i386/Kconfig --- c/arch/i386/Kconfig 2005-06-30 21:03:57.000000000 +0200 +++ badram/arch/i386/Kconfig 2005-07-01 11:35:48.000000000 +0200 @@ -747,6 +747,23 @@ config X86_PAE depends on HIGHMEM64G default y +config BADRAM + bool "Work around bad spots in RAM" + default y + help + This small kernel extension makes it possible to use memory chips + which are not entirely correct. It works by never allocating the + places that are wrong. Those places are specified with the badram + boot option to LILO. Read Documentation/badram.txt and/or visit + http://home.zonnet.nl/vanrein/badram for information. + + This option co-operates well with a second boot option from LILO + that starts memtest86, which is able to automatically produce the + patterns for the commandline in case of memory trouble. + + It is safe to say 'Y' here, and it is advised because there is no + performance impact. + # Common NUMA Features config NUMA bool "Numa Memory Allocation and Scheduler Support" diff -pruNX dontdiff c/arch/i386/defconfig badram/arch/i386/defconfig --- c/arch/i386/defconfig 2005-06-30 21:03:57.000000000 +0200 +++ badram/arch/i386/defconfig 2005-07-01 11:35:48.000000000 +0200 @@ -114,6 +114,7 @@ CONFIG_X86_MCE_P4THERMAL=y CONFIG_NOHIGHMEM=y # CONFIG_HIGHMEM4G is not set # CONFIG_HIGHMEM64G is not set +CONFIG_BADRAM=y # CONFIG_MATH_EMULATION is not set CONFIG_MTRR=y # CONFIG_EFI is not set diff -pruNX dontdiff c/arch/i386/mm/init.c badram/arch/i386/mm/init.c --- c/arch/i386/mm/init.c 2005-06-30 21:03:58.000000000 +0200 +++ badram/arch/i386/mm/init.c 2005-07-01 11:40:12.000000000 +0200 @@ -265,25 +265,39 @@ static void __init permanent_kmaps_init( pkmap_page_table = pte; } -void __init one_highpage_init(struct page *page, int pfn, int bad_ppro) +/** + * @param bad set on return to whether the page is bad RAM + */ +void __init one_highpage_init(struct page *page, int pfn, int bad_ppro, + int *bad) { + *bad = 0; if (page_is_ram(pfn) && !(bad_ppro && page_kills_ppro(pfn))) { ClearPageReserved(page); set_page_count(page, 1); - __free_page(page); +#ifdef CONFIG_BADRAM + if (PageBad(page)) + *bad = 1; + else +#endif + __free_page(page); totalhigh_pages++; } else SetPageReserved(page); } #ifdef CONFIG_NUMA -extern void set_highmem_pages_init(int); +extern void set_highmem_pages_init(int, *int); #else -static void __init set_highmem_pages_init(int bad_ppro) +static void __init set_highmem_pages_init(int bad_ppro, int *pbad) { int pfn; - for (pfn = highstart_pfn; pfn < highend_pfn; pfn++) - one_highpage_init(pfn_to_page(pfn), pfn, bad_ppro); + int bad; + for (pfn = highstart_pfn; pfn < highend_pfn; pfn++) { + one_highpage_init(pfn_to_page(pfn), pfn, bad_ppro, &bad); + if (bad) + *pbad++; + } totalram_pages += totalhigh_pages; } #endif /* CONFIG_FLATMEM */ @@ -291,7 +305,7 @@ static void __init set_highmem_pages_ini #else #define kmap_init() do { } while (0) #define permanent_kmaps_init(pgd_base) do { } while (0) -#define set_highmem_pages_init(bad_ppro) do { } while (0) +#define set_highmem_pages_init(bad_ppro, pbad) do { } while (0) #endif /* CONFIG_HIGHMEM */ unsigned long long __PAGE_KERNEL = _PAGE_KERNEL; @@ -536,7 +550,7 @@ static struct kcore_list kcore_mem, kcor void __init mem_init(void) { extern int ppro_with_ram_bug(void); - int codesize, reservedpages, datasize, initsize; + int codesize, reservedpages, badpages, datasize, initsize; int tmp; int bad_ppro; @@ -569,14 +583,20 @@ void __init mem_init(void) totalram_pages += free_all_bootmem(); reservedpages = 0; - for (tmp = 0; tmp < max_low_pfn; tmp++) + badpages = 0; + for (tmp = 0; tmp < max_low_pfn; tmp++) { /* - * Only count reserved RAM pages + * Only count reserved and bad RAM pages */ if (page_is_ram(tmp) && PageReserved(pfn_to_page(tmp))) reservedpages++; +#ifdef CONFIG_BADRAM + if (page_is_ram(tmp) && PageBad(pfn_to_page(tmp))) + badpages++; +#endif + } - set_highmem_pages_init(bad_ppro); + set_highmem_pages_init(bad_ppro, &badpages); codesize = (unsigned long) &_etext - (unsigned long) &_text; datasize = (unsigned long) &_edata - (unsigned long) &_etext; @@ -586,6 +606,18 @@ void __init mem_init(void) kclist_add(&kcore_vmalloc, (void *)VMALLOC_START, VMALLOC_END-VMALLOC_START); +#ifdef CONFIG_BADRAM + printk(KERN_INFO "Memory: %luk/%luk available (%dk kernel code, %dk reserved, %dk data, %dk init, %ldk highmem, %dk BadRAM)\n", + (unsigned long) nr_free_pages() << (PAGE_SHIFT-10), + num_physpages << (PAGE_SHIFT-10), + codesize >> 10, + reservedpages << (PAGE_SHIFT-10), + datasize >> 10, + initsize >> 10, + (unsigned long) (totalhigh_pages << (PAGE_SHIFT-10)), + badpages << (PAGE_SHIFT-10) + ); +#else printk(KERN_INFO "Memory: %luk/%luk available (%dk kernel code, %dk reserved, %dk data, %dk init, %ldk highmem)\n", (unsigned long) nr_free_pages() << (PAGE_SHIFT-10), num_physpages << (PAGE_SHIFT-10), @@ -595,6 +627,7 @@ void __init mem_init(void) initsize >> 10, (unsigned long) (totalhigh_pages << (PAGE_SHIFT-10)) ); +#endif #ifdef CONFIG_X86_PAE if (!cpu_has_pae) diff -pruNX dontdiff c/arch/i386/mm/pgtable.c badram/arch/i386/mm/pgtable.c --- c/arch/i386/mm/pgtable.c 2005-06-30 21:03:58.000000000 +0200 +++ badram/arch/i386/mm/pgtable.c 2005-07-01 11:41:20.000000000 +0200 @@ -24,7 +24,7 @@ void show_mem(void) { - int total = 0, reserved = 0; + int total = 0, reserved = 0, badram = 0; int shared = 0, cached = 0; int highmem = 0; struct page *page; @@ -43,6 +43,10 @@ void show_mem(void) highmem++; if (PageReserved(page)) reserved++; +#ifdef CONFIG_BADRAM + else if (PageBad(page)) + badram++; +#endif else if (PageSwapCache(page)) cached++; else if (page_count(page)) @@ -52,6 +56,9 @@ void show_mem(void) printk(KERN_INFO "%d pages of RAM\n", total); printk(KERN_INFO "%d pages of HIGHMEM\n", highmem); printk(KERN_INFO "%d reserved pages\n", reserved); +#ifdef CONFIG_BADRAM + printk(KERN_INFO "%d pages of BadRAM\n", badram); +#endif printk(KERN_INFO "%d pages shared\n", shared); printk(KERN_INFO "%d pages swap cached\n", cached); diff -pruNX dontdiff c/badram-2.6.11 badram/badram-2.6.11 --- c/badram-2.6.11 1970-01-01 01:00:00.000000000 +0100 +++ badram/badram-2.6.11 2005-07-01 11:33:27.000000000 +0200 @@ -0,0 +1,712 @@ +diff -pruNX nodiff o/arch/i386/defconfig p/arch/i386/defconfig +--- o/arch/i386/defconfig 2005-03-02 08:38:12.000000000 +0100 ++++ p/arch/i386/defconfig 2005-03-07 10:04:39.659879500 +0100 +@@ -114,6 +114,7 @@ CONFIG_X86_MCE_P4THERMAL=y + CONFIG_NOHIGHMEM=y + # CONFIG_HIGHMEM4G is not set + # CONFIG_HIGHMEM64G is not set ++CONFIG_BADRAM=y + # CONFIG_MATH_EMULATION is not set + CONFIG_MTRR=y + # CONFIG_EFI is not set +diff -pruNX nodiff o/arch/i386/Kconfig p/arch/i386/Kconfig +--- o/arch/i386/Kconfig 2005-03-02 08:37:48.000000000 +0100 ++++ p/arch/i386/Kconfig 2005-03-07 10:03:24.949104900 +0100 +@@ -745,6 +745,23 @@ config X86_PAE + depends on HIGHMEM64G + default y + ++config BADRAM ++ bool "Work around bad spots in RAM" ++ default y ++ help ++ This small kernel extension makes it possible to use memory chips ++ which are not entirely correct. It works by never allocating the ++ places that are wrong. Those places are specified with the badram ++ boot option to LILO. Read Documentation/badram.txt and/or visit ++ http://home.zonnet.nl/vanrein/badram for information. ++ ++ This option co-operates well with a second boot option from LILO ++ that starts memtest86, which is able to automatically produce the ++ patterns for the commandline in case of memory trouble. ++ ++ It is safe to say 'Y' here, and it is advised because there is no ++ performance impact. ++ + # Common NUMA Features + config NUMA + bool "Numa Memory Allocation and Scheduler Support" +diff -pruNX nodiff o/arch/i386/mm/init.c p/arch/i386/mm/init.c +--- o/arch/i386/mm/init.c 2005-03-02 08:38:16.000000000 +0100 ++++ p/arch/i386/mm/init.c 2005-03-07 10:23:26.829855200 +0100 +@@ -268,33 +268,46 @@ void __init permanent_kmaps_init(pgd_t * + pkmap_page_table = pte; + } + +-void __init one_highpage_init(struct page *page, int pfn, int bad_ppro) ++/** ++ * @param bad set on return to whether the page is bad RAM ++ */ ++void __init one_highpage_init(struct page *page, int pfn, int bad_ppro, ++ int *bad) + { ++ *bad = 0; + if (page_is_ram(pfn) && !(bad_ppro && page_kills_ppro(pfn))) { + ClearPageReserved(page); + set_page_count(page, 1); +- __free_page(page); ++#ifdef CONFIG_BADRAM ++ if (PageBad(page)) ++ *bad = 1; ++ else ++#endif ++ __free_page(page); + totalhigh_pages++; + } else + SetPageReserved(page); + } + + #ifdef CONFIG_NUMA +-extern void set_highmem_pages_init(int); ++extern void set_highmem_pages_init(int, *int); + #else +-static void __init set_highmem_pages_init(int bad_ppro) ++static void __init set_highmem_pages_init(int bad_ppro, int *pbad) + { + int pfn; +- for (pfn = highstart_pfn; pfn < highend_pfn; pfn++) +- one_highpage_init(pfn_to_page(pfn), pfn, bad_ppro); ++ int bad; ++ for (pfn = highstart_pfn; pfn < highend_pfn; pfn++) { ++ one_highpage_init(pfn_to_page(pfn), pfn, bad_ppro, &bad); ++ if (bad) *pbad++; ++ } + totalram_pages += totalhigh_pages; + } + #endif /* CONFIG_FLATMEM */ + + #else + #define kmap_init() do { } while (0) + #define permanent_kmaps_init(pgd_base) do { } while (0) +-#define set_highmem_pages_init(bad_ppro) do { } while (0) ++#define set_highmem_pages_init(bad_ppro, pbad) do { } while (0) + #endif /* CONFIG_HIGHMEM */ + + unsigned long long __PAGE_KERNEL = _PAGE_KERNEL; +@@ -568,7 +581,7 @@ static struct kcore_list kcore_mem, kcor + void __init mem_init(void) + { + extern int ppro_with_ram_bug(void); +- int codesize, reservedpages, datasize, initsize; ++ int codesize, reservedpages, badpages, datasize, initsize; + int tmp; + int bad_ppro; + +@@ -601,14 +614,20 @@ void __init mem_init(void) + totalram_pages += __free_all_bootmem(); + + reservedpages = 0; +- for (tmp = 0; tmp < max_low_pfn; tmp++) ++ badpages = 0; ++ for (tmp = 0; tmp < max_low_pfn; tmp++) { + /* +- * Only count reserved RAM pages ++ * Only count reserved and bad RAM pages + */ + if (page_is_ram(tmp) && PageReserved(pfn_to_page(tmp))) + reservedpages++; ++#ifdef CONFIG_BADRAM ++ if (page_is_ram(tmp) && PageBad(pfn_to_page(tmp))) ++ badpages++; ++#endif ++ } + +- set_highmem_pages_init(bad_ppro); ++ set_highmem_pages_init(bad_ppro, &badpages); + + codesize = (unsigned long) &_etext - (unsigned long) &_text; + datasize = (unsigned long) &_edata - (unsigned long) &_etext; +@@ -618,6 +637,18 @@ void __init mem_init(void) + kclist_add(&kcore_vmalloc, (void *)VMALLOC_START, + VMALLOC_END-VMALLOC_START); + ++#ifdef CONFIG_BADRAM ++ printk(KERN_INFO "Memory: %luk/%luk available (%dk kernel code, %dk reserved, %dk data, %dk init, %ldk highmem, %dk BadRAM)\n", ++ (unsigned long) nr_free_pages() << (PAGE_SHIFT-10), ++ num_physpages << (PAGE_SHIFT-10), ++ codesize >> 10, ++ reservedpages << (PAGE_SHIFT-10), ++ datasize >> 10, ++ initsize >> 10, ++ (unsigned long) (totalhigh_pages << (PAGE_SHIFT-10)), ++ badpages << (PAGE_SHIFT-10) ++ ); ++#else + printk(KERN_INFO "Memory: %luk/%luk available (%dk kernel code, %dk reserved, %dk data, %dk init, %ldk highmem)\n", + (unsigned long) nr_free_pages() << (PAGE_SHIFT-10), + num_physpages << (PAGE_SHIFT-10), +@@ -627,6 +658,7 @@ void __init mem_init(void) + initsize >> 10, + (unsigned long) (totalhigh_pages << (PAGE_SHIFT-10)) + ); ++#endif + + #ifdef CONFIG_X86_PAE + if (!cpu_has_pae) +diff -pruNX nodiff o/arch/i386/mm/pgtable.c p/arch/i386/mm/pgtable.c +--- o/arch/i386/mm/pgtable.c 2005-03-02 08:38:34.000000000 +0100 ++++ p/arch/i386/mm/pgtable.c 2005-03-07 10:26:27.422449400 +0100 +@@ -24,7 +24,7 @@ + + void show_mem(void) + { +- int total = 0, reserved = 0; ++ int total = 0, reserved = 0, badram = 0; + int shared = 0, cached = 0; + int highmem = 0; + struct page *page; +@@ -42,6 +42,10 @@ void show_mem(void) + highmem++; + if (PageReserved(page)) + reserved++; ++#ifdef CONFIG_BADRAM ++ else if (PageBad(page)) ++ badram++; ++#endif + else if (PageSwapCache(page)) + cached++; + else if (page_count(page)) +@@ -51,6 +55,9 @@ void show_mem(void) + printk("%d pages of RAM\n", total); + printk("%d pages of HIGHMEM\n",highmem); + printk("%d reserved pages\n",reserved); ++#ifdef CONFIG_BADRAM ++ printk("%d pages of BadRAM\n",badram); ++#endif + printk("%d pages shared\n",shared); + printk("%d pages swap cached\n",cached); + } +diff -pruNX nodiff o/CREDITS p/CREDITS +--- o/CREDITS 2005-03-02 08:38:12.000000000 +0100 ++++ p/CREDITS 2005-03-07 09:57:45.449122700 +0100 +@@ -2750,6 +2750,15 @@ S: 6 Karen Drive + S: Malvern, Pennsylvania 19355 + S: USA + ++N: Rick van Rein ++E: rick@vanrein.org ++W: http://rick.vanrein.org/ ++D: Memory, the BadRAM subsystem dealing with statically challanged RAM modules. ++S: Binnenes 67 ++S: 9407 CX Assen ++S: The Netherlands ++P: 1024D/89754606 CD46 B5F2 E876 A5EE 9A85 1735 1411 A9C2 8975 4606 ++ + N: Stefan Reinauer + E: stepan@linux.de + W: http://www.freiburg.linux.de/~stepan/ +diff -pruNX nodiff o/Documentation/badram.txt p/Documentation/badram.txt +--- o/Documentation/badram.txt 1970-01-01 01:00:00.000000000 +0100 ++++ p/Documentation/badram.txt 2005-03-07 09:58:54.526363500 +0100 +@@ -0,0 +1,266 @@ ++INFORMATION ON USING BAD RAM MODULES ++==================================== ++ ++Introduction ++ RAM is getting smaller and smaller, and as a result, also more and more ++ vulnerable. This makes the manufacturing of hardware more expensive, ++ since an excessive amount of RAM chips must be discarded on account of ++ a single cell that is wrong. Similarly, static discharge may damage a ++ RAM module forever, which is usually remedied by replacing it ++ entirely. ++ ++ This is not necessary, as the BadRAM code shows: By informing the Linux ++ kernel which addresses in a RAM are damaged, the kernel simply avoids ++ ever allocating such addresses but makes all the rest available. ++ ++Reasons for this feature ++ There are many reasons why this kernel feature is useful: ++ - Chip manufacture is resource intensive; waste less and sleep better ++ - It's another chance to promote Linux as "the flexible OS" ++ - Some laptops have their RAM soldered in... and then it fails! ++ - It's plain cool ;-) ++ ++Running example ++ To run this project, I was given two DIMMs, 32 MB each. One, that we ++ shall use as a running example in this text, contained 512 faulty bits, ++ spread over 1/4 of the address range in a regular pattern. Some tricks ++ with a RAM tester and a few binary calculations were sufficient to ++ write these faults down in 2 longword numbers. ++ ++ The kernel recognised the correct number of pages with faults and did ++ not give them out for allocation. The allocation routines could ++ therefore progress as normally, without any adaption. ++ So, I gained 30 MB of DIMM which would otherwise have been thrown ++ away. After booting the kernel, the kernel behaved exactly as it ++ always had. ++ ++Initial checks ++ If you experience RAM trouble, first read /usr/src/linux/memory.txt ++ and try out the mem=4M trick to see if at least some initial parts ++ of your RAM work well. The BadRAM routines halt the kernel in panic ++ if the reserved area of memory (containing kernel stuff) contains ++ a faulty address. ++ ++Running a RAM checker ++ The memory checker is not built into the kernel, to avoid delays at ++ runtime. If you experience problems that may be caused by RAM, run ++ a good RAM checker, such as ++ http://reality.sgi.com/cbrady_denver/memtest86 ++ The output of a RAM checker provides addresses that went wrong. In ++ the 32 MB chip with 512 faulty bits mentioned above, the errors were ++ found in the 8MB-16MB range (the DIMM was in slot #0) at addresses ++ xxx42f4 ++ xxx62f4 ++ xxxc2f4 ++ xxxe2f4 ++ and the error was a "sticky 1 bit", a memory bit that stayed "1" no ++ matter what was written to it. The regularity of this pattern ++ suggests the death of a buffer at the output stages of a row on one of ++ the chips. I expect such regularity to be commonplace. Finding this ++ regularity currently is human effort, but it should not be hard to ++ alter a RAM checker to capture it in some sort of pattern, possibly ++ the BadRAM patterns described below. ++ ++ By the way, if you manage to get hold of memtest86 version 2.3 or ++ beyond, you can configure the printing mode to produce BadRAM patterns, ++ which find out exactly what you must enter on the LILO: commandline, ++ except that you shouldn't mention the added spacing. That means that ++ you can skip the following step, which saves you a *lot* of work. ++ ++ Also by the way, if your machine has the ISA memory gap in the 15M-16M ++ range unstoppable, Linux can get in trouble. One way of handling that ++ situation is by specifying the total memory size to Linux with a boot ++ parameter mem=... and then to tell it to treat the 15M-16M range as ++ faulty with an additional boot parameter, for instance: ++ mem=24M badram=0x00f00000,0xfff00000 ++ if you installed 24MB of RAM in total. ++ ++Capturing errors in a pattern ++ Instead of manually providing all 512 errors to the kernel, it's nicer ++ to generate a pattern. Since the regularity is based on address decoding ++ software, which generally takes certain bits into account and ignores ++ others, we shall provide a faulty address F, together with a bit mask M ++ that specifies which bits must be equal to F. In C code, an address A ++ is faulty if and only if ++ (F & M) == (A & M) ++ or alternately (closer to a hardware implementation): ++ ~((F ^ A) & M) ++ In the example 32 MB chip, we had the faulty addresses in 8MB-16MB: ++ xxx42f4 ....0100.... ++ xxx62f4 ....0110.... ++ xxxc2f4 ....1100.... ++ xxxe2f4 ....1110.... ++ The second column represents the alternating hex digit in binary form. ++ Apperantly, the first and one-but last binary digit can be anything, ++ so the binary mask for that part is 0101. The mask for the part after ++ this is 0xfff, and the part before should select anything in the range ++ 8MB-16MB, or 0x00800000-0x01000000; this is done with a bitmask ++ 0xff80xxxx. Combining these partial masks, we get: ++ F=0x008042f4 M=0xff805fff ++ That covers everything for this DIMM; for more complicated failing ++ DIMMs, or for a combination of multiple failing DIMMs, it can be ++ necessary to set up a number of such F/M pairs. ++ ++Rebooting Linux ++ Now that these patterns are known (and double-checked, the calculations ++ are highly error-prone... it would be neat to test them in the RAM ++ checker...) we simply restart Linux with these F/M pairs as a parameter. ++ If you normally boot as follows: ++ LILO: linux ++ you should now boot with ++ LILO: linux badram=0x008042f4,0xff805fff ++ or perhaps by mentioning more F/M pairs in an order F0,M0,F1,M1,... ++ When you provide an odd number of arguments to badram, the default mask ++ 0xffffffff (only one address matched) is applied to the pattern. ++ ++ Beware of the commandline length. At least up to LILO version 0.21, ++ the commandline is cut off after the 78th character; later versions ++ may go as far as the kernel goes, namely 255 characters. In no way is ++ it possible to enter more than 10 numbers to the badram boot option. ++ ++ When the kernel now boots, it should not give any trouble with RAM. ++ Mind you, this is under the assumption that the kernel and its data ++ storage do not overlap an erroneous part. If this happens, and the ++ kernel does not choke on it right away, it will stop with a panic. ++ You will need to provide a RAM where the initial, say 2MB, is faultless. ++ ++ Now look up your memory status with ++ dmesg | grep ^Memory: ++ which prints a single line with information like ++ Memory: 158524k/163840k available ++ (940k kernel code, ++ 412k reserved, ++ 1856k data, ++ 60k init, ++ 0k highmem, ++ 2048k BadRAM) ++ The latter entry, the badram, is 2048k to represent the loss of 2MB ++ of general purpose RAM due to the errors. Or, positively rephrased, ++ instead of throwing out 32MB as useless, you only throw out 2MB. ++ ++ If the system is stable (try compiling a few kernels, and do a few ++ finds in / or so) you may add the boot parameter to /etc/lilo.conf ++ as a line to _all_ the kernels that handle this trouble with a line ++ append="badram=0x008042f4,0xff805fff" ++ after which you run "lilo". ++ Warning: Don't experiment with these settings on your only boot image. ++ If the BadRAM overlays kernel code, data, init, or other reserved ++ memory, the kernel will halt in panic. Try settings on a test boot ++ image first, and if you get a panic you should change the order of ++ your DIMMs [which may involve buying a new one just to be able to ++ change the order]. ++ ++ You are allowed to enter any number of BadRAM patterns in all the ++ places documented in this file. They will all apply. It is even ++ possible to mention several BadRAM patterns in a single place. The ++ completion of an odd number of arguments with the default mask is ++ done separately for each badram=... option. ++ ++Kernel Customisation ++ Some people prefer to enter their badram patterns in the kernel, and ++ this is also possible. In mm/page_alloc.c there is an array of unsigned ++ long integers into which the parameters can be entered, prefixed with ++ the number of integers (twice the number of patterns). The array is ++ named badram_custom and it will be added to the BadRAM list whenever an ++ option 'badram' is provided on the commandline when booting, either ++ with or without additional patterns. ++ ++ For the previous example, the code would become ++ ++ static unsigned long __initdata badram_custom[] = { ++ 2, // Number of longwords that follow, as F/M pairs ++ 0x008042f4L, 0xff805fffL, ++ }; ++ ++ Even on this place you may assume the default mask to be filled in ++ when you enter an odd number of longwords. Specify the number of ++ longwords to be 0 to avoid influence of this custom BadRAM list. ++ ++BadRAM classification ++ This technique may start a lively market for "dead" RAM. It is important ++ to realise that some RAMs are more dead than others. So, instead of ++ just providing a RAM size, it is also important to know the BadRAM ++ class, which is defined as follows: ++ ++ A BadRAM class N means that at most 2^N bytes have a problem, ++ and that all problems with the RAMs are persistent: They ++ are predictable and always show up. ++ ++ The DIMM that serves as an example here was of class 9, since 512=2^9 ++ errors were found. Higher classes are worse, "correct" RAM is of class ++ -1 (or even less, at your choice). ++ Class N also means that the bitmask for your chip (if there's just one, ++ that is) counts N bits "0" and it means that (if no faults fall in the ++ same page) an amount of 2^N*PAGESIZE memory is lost, in the example on ++ an i386 architecture that would be 2^9*4k=2MB, which accounts for the ++ initial claim of 30MB RAM gained with this DIMM. ++ ++ Note that this scheme has deliberately been defined to be independent ++ of memory technology and of computer architecture. ++ ++Known Bugs ++ LILO is known to cut off commandlines which are too long. For the ++ lilo-0.21 distribution, a commandline may not exceed 78 characters, ++ while actually, 255 would be possible [on i386, kernel 2.2.16]. ++ LILO does _not_ report too-long commandlines, but the error will ++ show up as either a panic at boot time, stating ++ panic: BadRAM page in initial area ++ or the dmesg line starting with Memory: will mention an unpredicted ++ number of kilobytes. (Note that the latter number only includes ++ errors in accessed memory.) ++ ++Future Possibilities ++ It would be possible to use even more of the faulty RAMs by employing ++ them for slabs. The smaller allocation granularity of slabs makes it ++ possible to throw out just, say, 32 bytes surrounding an error. This ++ would mean that the example DIMM only looses 16kB instead of 2MB. ++ It might even be possible to allocate the slabs in such a way that, ++ where possible, the remaining bytes in a slab structure are allocated ++ around the error, reducing the RAM loss to 0 in the optimal situation! ++ ++ However, this yield is somewhat faked: It is possible to provide 512 ++ pages of 32-byte slabs, but it is not certain that anyone would use ++ that many 32-byte slabs at any time. ++ ++ A better solution might be to alter the page allocation for a slab to ++ have a preference for BadRAM pages, and given those a special treatment. ++ This way, the BadRAM would be spread over all the slabs, which seems ++ more likely to be a `true' pay-off. This would yield more overhead at ++ slab allocation time, but on the other hand, by the nature of slabs, ++ such allocations are made as rare as possible, so it might not matter ++ that much. I am uncertain where to go. ++ ++ Many suggestions have been made to insert a RAM checker at boot time; ++ since this would leave the time to do only very meager checking, it ++ is not a reasonable option; we already have a BIOS doing that in most ++ systems! ++ ++ It would be interesting to integrate this functionality with the ++ self-verifying nature of ECC RAM. These memories can even distinguish ++ between recorable and unrecoverable errors! Such memory has been ++ handled in older operating systems by `testing' once-failed memory ++ blocks for a while, by placing only (reloadable) program code in it. ++ Unfortunately, I possess no faulty ECC modules to work this out. ++ ++Names and Places ++ The home page of this project is on ++ http://rick.vanrein.org/linux/badram ++ This page also links to Nico Schmoigl's experimental extensions to ++ this patch (with debugging and a few other fancy things). ++ ++ In case you have experiences with the BadRAM software which differ from ++ the test reportings on that site, I hope you will mail me with that ++ new information. ++ ++ The BadRAM project is an idea and implementation by ++ Rick van Rein ++ Binnenes 67 ++ 9407 CX Assen ++ The Netherlands ++ rick@vanrein.org ++ If you like it, a postcard would be much appreciated ;-) ++ ++ ++ Enjoy, ++ -Rick. ++ +diff -pruNX nodiff o/Documentation/kernel-parameters.txt p/Documentation/kernel-parameters.txt +--- o/Documentation/kernel-parameters.txt 2005-03-02 08:38:34.000000000 +0100 ++++ p/Documentation/kernel-parameters.txt 2005-03-07 10:00:44.634195900 +0100 +@@ -26,6 +26,7 @@ restrictions referred to are that the re + APIC APIC support is enabled. + APM Advanced Power Management support is enabled. + AX25 Appropriate AX.25 support is enabled. ++ BADRAM Support for faulty RAM chips is enabled. + CD Appropriate CD support is enabled. + DEVFS devfs support is enabled. + DRM Direct Rendering Management support is enabled. +@@ -251,6 +252,8 @@ running once the system is up. + aztcd= [HW,CD] Aztech CD268 CDROM driver + Format: ,0x79 (?) + ++ badram= [BADRAM] Avoid allocating faulty RAM addresses. ++ + baycom_epp= [HW,AX25] + Format: , + +diff -pruNX nodiff o/Documentation/memory.txt p/Documentation/memory.txt +--- o/Documentation/memory.txt 2005-03-02 08:38:32.000000000 +0100 ++++ p/Documentation/memory.txt 2005-03-07 10:02:06.662820900 +0100 +@@ -18,6 +18,14 @@ systems. + as you add more memory. Consider exchanging your + motherboard. + ++ 4) A static discharge or production fault causes a RAM module ++ to have (predictable) errors, usually meaning that certain ++ bits cannot be set or reset. Instead of throwing away your ++ RAM module, you may read /usr/src/linux/Documentation/badram.txt ++ to learn how to detect, locate and circuimvent such errors ++ in your RAM module. ++ ++ + All of these problems can be addressed with the "mem=XXXM" boot option + (where XXX is the size of RAM to use in megabytes). + It can also tell Linux to use less memory than is actually installed. +@@ -49,6 +57,8 @@ Try: + Linux to using a very small amount of memory. Use "memmap="-option + together with "mem=" on systems with PCI to avoid physical address + space collisions. ++ If this helps, read Documentation/badram.txt to learn how to ++ find and circumvent memory errors. + + + Other tricks: +diff -pruNX nodiff o/include/asm-i386/page.h p/include/asm-i386/page.h +--- o/include/asm-i386/page.h 2005-03-02 08:37:48.000000000 +0100 ++++ p/include/asm-i386/page.h 2005-03-07 10:27:57.859370600 +0100 +@@ -140,6 +140,7 @@ extern int sysctl_legacy_va_layout; + #define pfn_valid(pfn) ((pfn) < max_mapnr) + #endif /* !CONFIG_DISCONTIGMEM */ + #define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT) ++#define phys_to_page(x) (mem_map + ((unsigned long)(x) >> PAGE_SHIFT)) + + #define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT) + +diff -pruNX nodiff o/include/linux/page-flags.h p/include/linux/page-flags.h +--- o/include/linux/page-flags.h 2005-03-02 08:38:12.000000000 +0100 ++++ p/include/linux/page-flags.h 2005-03-07 10:29:36.671238200 +0100 +@@ -75,7 +75,7 @@ + #define PG_mappedtodisk 17 /* Has blocks allocated on-disk */ + #define PG_reclaim 18 /* To be reclaimed asap */ + #define PG_nosave_free 19 /* Free, should not be written */ +- ++#define PG_badram 20 /* BadRam page */ + + /* + * Global page accounting. One instance per CPU. Only unsigned longs are +@@ -161,6 +161,10 @@ extern void __mod_page_state(unsigned of + __mod_page_state(offset, (delta)); \ + } while (0) + ++#define PageBad(page) test_bit(PG_badram, &(page)->flags) ++#define PageSetBad(page) set_bit(PG_badram, &(page)->flags) ++#define PageTestandSetBad(page) test_and_set_bit(PG_badram, &(page)->flags) ++ + /* + * Manipulation of page state flags + */ +diff -pruNX nodiff o/mm/bootmem.c p/mm/bootmem.c +--- o/mm/bootmem.c 2005-03-02 08:37:52.000000000 +0100 ++++ p/mm/bootmem.c 2005-03-07 10:32:43.279418900 +0100 +@@ -269,10 +269,12 @@ static unsigned long __init free_all_boo + page = virt_to_page(phys_to_virt(bdata->node_boot_start)); + idx = bdata->node_low_pfn - (bdata->node_boot_start >> PAGE_SHIFT); + map = bdata->node_bootmem_map; ++#ifndef CONFIG_BADRAM /* no idea if this is really needed */ + /* Check physaddr is O(LOG2(BITS_PER_LONG)) page aligned */ + if (bdata->node_boot_start == 0 || + ffs(bdata->node_boot_start) - PAGE_SHIFT > ffs(BITS_PER_LONG)) + gofast = 1; ++#endif + for (i = 0; i < idx; ) { + unsigned long v = ~map[i / BITS_PER_LONG]; + if (gofast && v == ~0UL) { +@@ -296,8 +298,13 @@ static unsigned long __init free_all_boo + if (v & m) { + count++; + __ClearPageReserved(page); +- set_page_refs(page, 0); +- __free_page(page); ++#ifdef CONFIG_BADRAM ++ if (!PageBad(page)) ++#endif ++ { ++ set_page_count(page, 1); ++ __free_page(page); ++ } + } + } + } else { +@@ -316,8 +323,13 @@ static unsigned long __init free_all_boo + for (i = 0; i < ((bdata->node_low_pfn-(bdata->node_boot_start >> PAGE_SHIFT))/8 + PAGE_SIZE-1)/PAGE_SIZE; i++,page++) { + count++; + __ClearPageReserved(page); +- set_page_count(page, 1); +- __free_page(page); ++#ifdef CONFIG_BADRAM ++ if (!PageBad(page)) ++#endif ++ { ++ set_page_count(page, 1); ++ __free_page(page); ++ } + } + total += count; + bdata->node_bootmem_map = NULL; +diff -pruNX nodiff o/mm/page_alloc.c p/mm/page_alloc.c +--- o/mm/page_alloc.c 2005-03-02 08:38:34.000000000 +0100 ++++ p/mm/page_alloc.c 2005-03-07 10:34:51.247349900 +0100 +@@ -10,6 +10,7 @@ + * Reshaped it to be a zoned allocator, Ingo Molnar, Red Hat, 1999 + * Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999 + * Zone balancing, Kanoj Sarcar, SGI, Jan 2000 ++ * BadRAM handling, Rick van Rein, Feb 2001 + * Per cpu hot/cold page lists, bulk allocation, Martin J. Bligh, Sept 2002 + * (lots of bits borrowed from Ingo Molnar & Andrew Morton) + */ +@@ -2153,3 +2154,94 @@ void *__init alloc_large_system_hash(con + + return table; + } ++ ++#ifdef CONFIG_BADRAM ++ ++/* Given a pointed-at address and a mask, increment the page so that the ++ * mask hides the increment. Return 0 if no increment is possible. ++ */ ++static int __init next_masked_address (unsigned long *addrp, unsigned long mask) ++{ ++ unsigned long inc=1; ++ unsigned long newval = *addrp; ++ while (inc & mask) ++ inc += inc; ++ while (inc != 0) { ++ newval += inc; ++ newval &= ~mask; ++ newval |= ((*addrp) & mask); ++ if (newval > *addrp) { ++ *addrp = newval; ++ return 1; ++ } ++ do { ++ inc += inc; ++ } while (inc & ~mask); ++ while (inc & mask) ++ inc += inc; ++ } ++ return 0; ++} ++ ++ ++void __init badram_markpages (int argc, unsigned long *argv) { ++ unsigned long addr, mask; ++ while (argc-- > 0) { ++ addr = *argv++; ++ mask = (argc-- > 0) ? *argv++ : ~0L; ++ mask |= ~PAGE_MASK; /* Optimalisation */ ++ addr &= mask; /* Normalisation */ ++ do { ++ struct page *pg = phys_to_page(addr); ++ printk ("%05lx ", __pa(__va(addr)) >> PAGE_SHIFT); ++ printk ("=%05lx/%05lx ", (unsigned long)(pg-mem_map), ++ max_mapnr); ++ /* if (VALID_PAGE(pg)) {*/ ++ if (PageTestandSetBad (pg)) { ++ reserve_bootmem (addr, PAGE_SIZE); ++ printk ("BAD "); ++ } ++ else printk ("BFR "); ++ /* }*/ ++ /* else printk ("INV ");*/ ++ } while (next_masked_address (&addr,mask)); ++ } ++} ++ ++ ++/*********** CONFIG_BADRAM: CUSTOMISABLE SECTION STARTS HERE ******************/ ++ ++ ++/* Enter your custom BadRAM patterns here as pairs of unsigned long integers. */ ++/* For more information on these F/M pairs, refer to Documentation/badram.txt */ ++ ++ ++static unsigned long __initdata badram_custom[] = { ++ 0, /* Number of longwords that follow, as F/M pairs */ ++}; ++ ++ ++/*********** CONFIG_BADRAM: CUSTOMISABLE SECTION ENDS HERE ********************/ ++ ++ ++static int __init badram_setup (char *str) ++{ ++ unsigned long opts[3]; ++ if (!mem_map) BUG(); ++ printk ("PAGE_OFFSET=0x%08lx\n", PAGE_OFFSET); ++ printk ("BadRAM option is %s\n", str); ++ if (*str++ == '=') ++ while ((str = get_options (str, 3, (int *) opts), *opts)) { ++ printk (" --> marking 0x%08lx, 0x%08lx [%ld]\n", ++ opts[1], opts[2], opts[0]); ++ badram_markpages (*opts, opts+1); ++ if (*opts == 1) ++ break; ++ }; ++ badram_markpages (*badram_custom, badram_custom+1); ++ return 0; ++} ++ ++__setup("badram", badram_setup); ++ ++#endif /* CONFIG_BADRAM */ diff -pruNX dontdiff c/include/asm-i386/page.h badram/include/asm-i386/page.h --- c/include/asm-i386/page.h 2005-06-30 21:04:20.000000000 +0200 +++ badram/include/asm-i386/page.h 2005-07-01 11:35:48.000000000 +0200 @@ -146,6 +146,7 @@ extern int page_is_ram(unsigned long pag #define pfn_valid(pfn) ((pfn) < max_mapnr) #endif /* CONFIG_FLATMEM */ #define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT) +#define phys_to_page(x) (mem_map + ((unsigned long)(x) >> PAGE_SHIFT)) #define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT) diff -pruNX dontdiff c/include/linux/page-flags.h badram/include/linux/page-flags.h --- c/include/linux/page-flags.h 2005-06-30 21:04:22.000000000 +0200 +++ badram/include/linux/page-flags.h 2005-07-01 11:42:06.000000000 +0200 @@ -75,6 +75,7 @@ #define PG_reclaim 17 /* To be reclaimed asap */ #define PG_nosave_free 18 /* Free, should not be written */ #define PG_uncached 19 /* Page has been mapped as uncached */ +#define PG_badram 20 /* BadRAR page */ /* * Global page accounting. One instance per CPU. Only unsigned longs are @@ -161,6 +162,10 @@ extern void __mod_page_state(unsigned lo __mod_page_state(offset, (delta)); \ } while (0) +#define PageBad(page) test_bit(PG_badram, &(page)->flags) +#define PageSetBad(page) set_bit(PG_badram, &(page)->flags) +#define PageTestandSetBad(page) test_and_set_bit(PG_badram, &(page)->flags) + /* * Manipulation of page state flags */ diff -pruNX dontdiff c/mm/bootmem.c badram/mm/bootmem.c --- c/mm/bootmem.c 2005-06-30 21:04:24.000000000 +0200 +++ badram/mm/bootmem.c 2005-07-01 11:35:48.000000000 +0200 @@ -278,10 +278,12 @@ static unsigned long __init free_all_boo pfn = bdata->node_boot_start >> PAGE_SHIFT; idx = bdata->node_low_pfn - (bdata->node_boot_start >> PAGE_SHIFT); map = bdata->node_bootmem_map; +#ifndef CONFIG_BADRAM /* no idea if this is really needed */ /* Check physaddr is O(LOG2(BITS_PER_LONG)) page aligned */ if (bdata->node_boot_start == 0 || ffs(bdata->node_boot_start) - PAGE_SHIFT > ffs(BITS_PER_LONG)) gofast = 1; +#endif for (i = 0; i < idx; ) { unsigned long v = ~map[i / BITS_PER_LONG]; @@ -309,8 +311,13 @@ static unsigned long __init free_all_boo if (v & m) { count++; __ClearPageReserved(page); - set_page_refs(page, 0); - __free_page(page); +#ifdef CONFIG_BADRAM + if (!PageBad(page)) +#endif + { + set_page_count(page, 1); + __free_page(page); + } } } } else { @@ -329,8 +336,13 @@ static unsigned long __init free_all_boo for (i = 0; i < ((bdata->node_low_pfn-(bdata->node_boot_start >> PAGE_SHIFT))/8 + PAGE_SIZE-1)/PAGE_SIZE; i++,page++) { count++; __ClearPageReserved(page); - set_page_count(page, 1); - __free_page(page); +#ifdef CONFIG_BADRAM + if (!PageBad(page)) +#endif + { + set_page_count(page, 1); + __free_page(page); + } } total += count; bdata->node_bootmem_map = NULL; diff -pruNX dontdiff c/mm/page_alloc.c badram/mm/page_alloc.c --- c/mm/page_alloc.c 2005-06-30 21:04:24.000000000 +0200 +++ badram/mm/page_alloc.c 2005-07-01 11:35:48.000000000 +0200 @@ -10,6 +10,7 @@ * Reshaped it to be a zoned allocator, Ingo Molnar, Red Hat, 1999 * Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999 * Zone balancing, Kanoj Sarcar, SGI, Jan 2000 + * BadRAM handling, Rick van Rein, Feb 2001 * Per cpu hot/cold page lists, bulk allocation, Martin J. Bligh, Sept 2002 * (lots of bits borrowed from Ingo Molnar & Andrew Morton) */ @@ -2558,3 +2559,94 @@ void *__init alloc_large_system_hash(con return table; } + +#ifdef CONFIG_BADRAM + +/* Given a pointed-at address and a mask, increment the page so that the + * mask hides the increment. Return 0 if no increment is possible. + */ +static int __init next_masked_address (unsigned long *addrp, unsigned long mask) +{ + unsigned long inc=1; + unsigned long newval = *addrp; + while (inc & mask) + inc += inc; + while (inc != 0) { + newval += inc; + newval &= ~mask; + newval |= ((*addrp) & mask); + if (newval > *addrp) { + *addrp = newval; + return 1; + } + do { + inc += inc; + } while (inc & ~mask); + while (inc & mask) + inc += inc; + } + return 0; +} + + +void __init badram_markpages (int argc, unsigned long *argv) { + unsigned long addr, mask; + while (argc-- > 0) { + addr = *argv++; + mask = (argc-- > 0) ? *argv++ : ~0L; + mask |= ~PAGE_MASK; /* Optimalisation */ + addr &= mask; /* Normalisation */ + do { + struct page *pg = phys_to_page(addr); + printk ("%05lx ", __pa(__va(addr)) >> PAGE_SHIFT); + printk ("=%05lx/%05lx ", (unsigned long)(pg-mem_map), + max_mapnr); + /* if (VALID_PAGE(pg)) {*/ + if (PageTestandSetBad (pg)) { + reserve_bootmem (addr, PAGE_SIZE); + printk ("BAD "); + } + else printk ("BFR "); + /* }*/ + /* else printk ("INV ");*/ + } while (next_masked_address (&addr,mask)); + } +} + + +/*********** CONFIG_BADRAM: CUSTOMISABLE SECTION STARTS HERE ******************/ + + +/* Enter your custom BadRAM patterns here as pairs of unsigned long integers. */ +/* For more information on these F/M pairs, refer to Documentation/badram.txt */ + + +static unsigned long __initdata badram_custom[] = { + 0, /* Number of longwords that follow, as F/M pairs */ +}; + + +/*********** CONFIG_BADRAM: CUSTOMISABLE SECTION ENDS HERE ********************/ + + +static int __init badram_setup (char *str) +{ + unsigned long opts[3]; + if (!mem_map) BUG(); + printk ("PAGE_OFFSET=0x%08lx\n", PAGE_OFFSET); + printk ("BadRAM option is %s\n", str); + if (*str++ == '=') + while ((str = get_options (str, 3, (int *) opts), *opts)) { + printk (" --> marking 0x%08lx, 0x%08lx [%ld]\n", + opts[1], opts[2], opts[0]); + badram_markpages (*opts, opts+1); + if (*opts == 1) + break; + }; + badram_markpages (*badram_custom, badram_custom+1); + return 0; +} + +__setup("badram", badram_setup); + +#endif /* CONFIG_BADRAM */