diff -Nurp linux/arch/i386/defconfig linux-badram/arch/i386/defconfig --- linux/arch/i386/defconfig 2006-06-23 14:06:55.000000000 +0200 +++ linux-badram/arch/i386/defconfig 2006-06-23 14:22:58.000000000 +0200 @@ -161,6 +161,7 @@ CONFIG_X86_MCE_NONFATAL=y CONFIG_NOHIGHMEM=y # CONFIG_HIGHMEM4G is not set # CONFIG_HIGHMEM64G is not set +CONFIG_BADRAM=y CONFIG_VMSPLIT_3G=y # CONFIG_VMSPLIT_3G_OPT is not set # CONFIG_VMSPLIT_2G is not set diff -Nurp linux/arch/i386/Kconfig linux-badram/arch/i386/Kconfig --- linux/arch/i386/Kconfig 2006-06-23 14:06:55.000000000 +0200 +++ linux-badram/arch/i386/Kconfig 2006-06-23 14:09:12.000000000 +0200 @@ -512,6 +512,23 @@ 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 -Nurp linux/arch/i386/mm/init.c linux-badram/arch/i386/mm/init.c --- linux/arch/i386/mm/init.c 2006-06-23 14:06:55.000000000 +0200 +++ linux-badram/arch/i386/mm/init.c 2006-06-23 14:21:33.000000000 +0200 @@ -268,25 +268,31 @@ static void __init permanent_kmaps_init( pkmap_page_table = pte; } -static void __meminit free_new_highpage(struct page *page) +static void __meminit free_new_highpage(struct page *page, int *bad) { init_page_count(page); - __free_page(page); + if (PageBad(page)) + *bad = 1; + else + __free_page(page); totalhigh_pages++; } -void __init add_one_highpage_init(struct page *page, int pfn, int bad_ppro) +void __init add_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); - free_new_highpage(page); + free_new_highpage(page, bad); } else SetPageReserved(page); } static int add_one_highpage_hotplug(struct page *page, unsigned long pfn) { - free_new_highpage(page); + int dummy; + free_new_highpage(page, &dummy); totalram_pages++; #ifdef CONFIG_FLATMEM max_mapnr = max(pfn, max_mapnr); @@ -309,13 +315,17 @@ void online_page(struct page *page) #ifdef CONFIG_NUMA -extern void set_highmem_pages_init(int); +extern void set_highmem_pages_init(int bad_ppro, int *pbad); #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++) - add_one_highpage_init(pfn_to_page(pfn), pfn, bad_ppro); + int bad; + for (pfn = highstart_pfn; pfn < highend_pfn; pfn++) { + add_one_highpage_init(pfn_to_page(pfn), pfn, bad_ppro, &bad); + if (bad) + (*pbad)++; + } totalram_pages += totalhigh_pages; } #endif /* CONFIG_FLATMEM */ @@ -323,7 +333,7 @@ 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; @@ -568,7 +578,7 @@ 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 +611,18 @@ 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++; + if (page_is_ram(tmp) && PageBad(pfn_to_page(tmp))) + badpages++; + } - 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 +632,18 @@ 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 +653,7 @@ void __init mem_init(void) initsize >> 10, (unsigned long) (totalhigh_pages << (PAGE_SHIFT-10)) ); +#endif #ifdef CONFIG_X86_PAE if (!cpu_has_pae) diff -Nurp linux/arch/i386/mm/pgtable.c linux-badram/arch/i386/mm/pgtable.c --- linux/arch/i386/mm/pgtable.c 2006-06-23 14:06:55.000000000 +0200 +++ linux-badram/arch/i386/mm/pgtable.c 2006-06-23 14:09:12.000000000 +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; @@ -45,6 +45,8 @@ void show_mem(void) highmem++; if (PageReserved(page)) reserved++; + else if (PageBad(page)) + badram++; else if (PageSwapCache(page)) cached++; else if (page_count(page)) @@ -55,6 +57,9 @@ 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 -Nurp linux/arch/x86_64/defconfig linux-badram/arch/x86_64/defconfig --- linux/arch/x86_64/defconfig 2006-06-23 14:06:56.000000000 +0200 +++ linux-badram/arch/x86_64/defconfig 2006-06-23 14:09:12.000000000 +0200 @@ -112,6 +112,7 @@ CONFIG_X86_CPUID=y CONFIG_X86_HT=y CONFIG_X86_IO_APIC=y CONFIG_X86_LOCAL_APIC=y +CONFIG_BADRAM=y CONFIG_MTRR=y CONFIG_SMP=y CONFIG_SCHED_SMT=y diff -Nurp linux/arch/x86_64/Kconfig linux-badram/arch/x86_64/Kconfig --- linux/arch/x86_64/Kconfig 2006-06-23 14:06:56.000000000 +0200 +++ linux-badram/arch/x86_64/Kconfig 2006-06-23 14:09:12.000000000 +0200 @@ -266,6 +266,23 @@ config SCHED_MC source "kernel/Kconfig.preempt" +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. + config NUMA bool "Non Uniform Memory Access (NUMA) Support" depends on SMP diff -Nurp linux/arch/x86_64/mm/init.c linux-badram/arch/x86_64/mm/init.c --- linux/arch/x86_64/mm/init.c 2006-06-23 14:06:56.000000000 +0200 +++ linux-badram/arch/x86_64/mm/init.c 2006-06-23 14:09:12.000000000 +0200 @@ -63,7 +63,7 @@ DEFINE_PER_CPU(struct mmu_gather, mmu_ga void show_mem(void) { - long i, total = 0, reserved = 0; + long i, total = 0, reserved = 0, badram = 0; long shared = 0, cached = 0; pg_data_t *pgdat; struct page *page; @@ -78,6 +78,8 @@ void show_mem(void) total++; if (PageReserved(page)) reserved++; + else if (PageBad(page)) + badram++; else if (PageSwapCache(page)) cached++; else if (page_count(page)) @@ -86,6 +88,9 @@ void show_mem(void) } printk(KERN_INFO "%lu pages of RAM\n", total); printk(KERN_INFO "%lu reserved pages\n",reserved); +#ifdef CONFIG_BADRAM + printk(KERN_INFO "%lu pages of BadRAM\n",badram); +#endif printk(KERN_INFO "%lu pages shared\n",shared); printk(KERN_INFO "%lu pages swap cached\n",cached); } diff -Nurp linux/CREDITS linux-badram/CREDITS --- linux/CREDITS 2006-06-23 14:06:54.000000000 +0200 +++ linux-badram/CREDITS 2006-06-23 14:09:12.000000000 +0200 @@ -2761,6 +2761,15 @@ 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: Haarlebrink 5 +S: 7544 WP Enschede +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 -Nurp linux/Documentation/badram.txt linux-badram/Documentation/badram.txt --- linux/Documentation/badram.txt 1970-01-01 01:00:00.000000000 +0100 +++ linux-badram/Documentation/badram.txt 2006-06-23 14:09:12.000000000 +0200 @@ -0,0 +1,276 @@ +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. + + If you use this patch on an x86_64 architecture, your addresses are + twice as long. Fill up with zeroes in the address and with f's in + the mask. The latter example would thus become: + mem=24M badram=0x0000000000f00000,0xfffffffffff00000 + The patch applies the changes to both i386 and x86_64 code bases + at the same time. Patching but not compiling maps the entire + source tree at once, which makes more sense than splitting the + patch into an i386 and x86_64 branch, because those two branches + could not be applied at the same time because they would overlap. + +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 + Haarlebrink 5 + 7544 WP Enschede + The Netherlands + rick@vanrein.org + If you like it, a postcard would be much appreciated ;-) + + + Enjoy, + -Rick. + diff -Nurp linux/Documentation/kernel-parameters.txt linux-badram/Documentation/kernel-parameters.txt --- linux/Documentation/kernel-parameters.txt 2006-06-23 14:06:54.000000000 +0200 +++ linux-badram/Documentation/kernel-parameters.txt 2006-06-23 14:09:12.000000000 +0200 @@ -34,6 +34,7 @@ parameter is applicable: 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. @@ -280,6 +281,8 @@ 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 -Nurp linux/Documentation/memory.txt linux-badram/Documentation/memory.txt --- linux/Documentation/memory.txt 2006-01-03 04:21:10.000000000 +0100 +++ linux-badram/Documentation/memory.txt 2006-06-23 14:09:12.000000000 +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 -Nurp linux/include/asm-i386/page.h linux-badram/include/asm-i386/page.h --- linux/include/asm-i386/page.h 2006-06-23 14:07:02.000000000 +0200 +++ linux-badram/include/asm-i386/page.h 2006-06-23 14:09:12.000000000 +0200 @@ -129,6 +129,7 @@ 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) pfn_to_page((unsigned long)(x) >> PAGE_SHIFT) #define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT) diff -Nurp linux/include/asm-x86_64/page.h linux-badram/include/asm-x86_64/page.h --- linux/include/asm-x86_64/page.h 2006-06-23 14:07:03.000000000 +0200 +++ linux-badram/include/asm-x86_64/page.h 2006-06-23 14:09:12.000000000 +0200 @@ -127,6 +127,7 @@ typedef struct { unsigned long pgprot; } #endif #define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT) +#define phys_to_page(x) pfn_to_page((unsigned long)(x) >> PAGE_SHIFT) #define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT) #define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT) diff -Nurp linux/include/linux/page-flags.h linux-badram/include/linux/page-flags.h --- linux/include/linux/page-flags.h 2006-06-23 14:07:03.000000000 +0200 +++ linux-badram/include/linux/page-flags.h 2006-06-23 14:27:09.000000000 +0200 @@ -89,6 +89,7 @@ #define PG_buddy 19 /* Page is free, on buddy lists */ #define PG_uncached 20 /* Page has been mapped as uncached */ +#define PG_badram 21 /* BadRam page */ /* * Global page accounting. One instance per CPU. Only unsigned longs are @@ -218,6 +219,14 @@ extern void __mod_page_state_offset(unsi mod_page_state_offset(state_zone_offset(zone, member), (delta)); \ } while (0) +#ifdef CONFIG_BADRAM +#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) +#else +#define PageBad(page) 0 +#endif + /* * Manipulation of page state flags */ diff -Nurp linux/lib/cmdline.c linux-badram/lib/cmdline.c --- linux/lib/cmdline.c 2006-01-03 04:21:10.000000000 +0100 +++ linux-badram/lib/cmdline.c 2006-06-23 14:09:12.000000000 +0200 @@ -81,6 +81,69 @@ char *get_options(const char *str, int n } /** + * get_longoption - Parse long from an option string + * @str: option string + * @plong: (output) long value parsed from @str + * + * Read a long from an option string; if available accept a subsequent + * comma as well. + * + * Return values: + * 0 : no long in string + * 1 : long found, no subsequent comma + * 2 : long found including a subsequent comma + */ + +int get_longoption (char **str, long *plong) +{ + char *cur = *str; + + if (!cur || !(*cur)) + return 0; + *plong = simple_strtol (cur, str, 0); + if (cur == *str) + return 0; + if (**str == ',') { + (*str)++; + return 2; + } + + return 1; +} + +/** + * get_longoptions - Parse a string into a list of longs + * @str: String to be parsed + * @nlongs: size of long array + * @longs: long array + * + * This function parses a string containing a comma-separated + * list of longs. The parse halts when the array is + * full, or when no more numbers can be retrieved from the + * string. + * + * Return value is the character in the string which caused + * the parse to end (typically a null terminator, if @str is + * completely parseable). + */ + +char *get_longoptions(const char *str, int nlongs, long *longs) +{ + int res, i = 1; + + while (i < nlongs) { + res = get_longoption ((char **)&str, longs + i); + if (res == 0) + break; + i++; + if (res == 1) + break; + } + longs[0] = i - 1; + return (char *)str; +} + +/** * memparse - parse a string with mem suffixes into a number * @ptr: Where parse begins * @retptr: (output) Pointer to next char after parse completes diff -Nurp linux/mm/bootmem.c linux-badram/mm/bootmem.c --- linux/mm/bootmem.c 2006-06-23 14:07:21.000000000 +0200 +++ linux-badram/mm/bootmem.c 2006-06-23 14:09:12.000000000 +0200 @@ -308,10 +308,12 @@ 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]; diff -Nurp linux/mm/page_alloc.c linux-badram/mm/page_alloc.c --- linux/mm/page_alloc.c 2006-06-23 14:07:22.000000000 +0200 +++ linux-badram/mm/page_alloc.c 2006-06-23 14:15:37.000000000 +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) */ @@ -462,9 +463,11 @@ void fastcall __init __free_pages_bootme { if (order == 0) { __ClearPageReserved(page); - set_page_count(page, 0); - set_page_refcounted(page); - __free_page(page); + if (!PageBad(page)) { + set_page_count(page, 0); + set_page_refcounted(page); + __free_page(page); + } } else { int loop; @@ -2843,3 +2846,88 @@ unsigned long page_to_pfn(struct page *p EXPORT_SYMBOL(pfn_to_page); EXPORT_SYMBOL(page_to_pfn); #endif /* CONFIG_OUT_OF_LINE_PFN_TO_PAGE */ + +#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(KERN_DEBUG "%016lx =%016lx\n", + addr >> PAGE_SHIFT, + (unsigned long)(pg-mem_map)); + if (PageTestandSetBad (pg)) + reserve_bootmem (addr, PAGE_SIZE); + } 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]; + BUG_ON(!mem_map); + printk (KERN_INFO "PAGE_OFFSET=0x%08lx\n", PAGE_OFFSET); + printk (KERN_INFO "BadRAM option is %s\n", str); + if (*str++ == '=') + while ((str = get_longoptions (str, 3, (int *) opts), *opts)) { + printk (KERN_INFO " --> 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 */