diff -u -r -N linux-2.4.23/CREDITS linux-2.4.23-badram/CREDITS --- linux-2.4.23/CREDITS Fri Nov 28 10:26:19 2003 +++ linux-2.4.23-badram/CREDITS Sat Nov 29 10:38:48 2003 @@ -2540,6 +2540,14 @@ 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 + N: Stefan Reinauer E: stepan@linux.de W: http://www.freiburg.linux.de/~stepan/ diff -u -r -N linux-2.4.23/Documentation/Configure.help linux-2.4.23-badram/Documentation/Configure.help --- linux-2.4.23/Documentation/Configure.help Fri Nov 28 10:26:19 2003 +++ linux-2.4.23-badram/Documentation/Configure.help Sat Nov 29 10:38:49 2003 @@ -22985,6 +22985,21 @@ This option allows you to run the kernel with data cache disabled. Say Y if you experience CPM lock-ups. +Work around bad spots in RAM +CONFIG_BADRAM + 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 /usr/src/linux/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. + # # m68k-specific kernel options # Documented by Chris Lawrence et al. @@ -28839,7 +28854,7 @@ # LocalWords: CramFs Cramfs uid cramfs AVM's kernelcapi PCIV cdrdao Cdparanoia # LocalWords: DMX Domex dmx wellington ftdi sio Accton Billington Corega FEter # LocalWords: MELCO LUA PNA Linksys SNC chkdsk AWACS Webcam RAMFS Ramfs ramfs -# LocalWords: ramfiles MAKEDEV pty WDTPCI APA apa +# LocalWords: ramfiles MAKEDEV pty WDTPCI APA apa BadRAM badram vanrein zonnet # # The following sets edit modes for GNU EMACS # Local Variables: diff -u -r -N linux-2.4.23/Documentation/badram.txt linux-2.4.23-badram/Documentation/badram.txt --- linux-2.4.23/Documentation/badram.txt Wed Dec 31 16:00:00 1969 +++ linux-2.4.23-badram/Documentation/badram.txt Sat Nov 29 10:38:49 2003 @@ -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 -u -r -N linux-2.4.23/Documentation/kernel-parameters.txt linux-2.4.23-badram/Documentation/kernel-parameters.txt --- linux-2.4.23/Documentation/kernel-parameters.txt Fri Nov 28 10:26:19 2003 +++ linux-2.4.23-badram/Documentation/kernel-parameters.txt Sat Nov 29 10:38:49 2003 @@ -14,6 +14,7 @@ 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. @@ -120,6 +121,9 @@ awe= [HW,SOUND] aztcd= [HW,CD] Aztec CD driver. + + badram= [BADRAM] Avoid allocating faulty RAM addresses. + baycom_epp= [HW,AX25] diff -u -r -N linux-2.4.23/Documentation/memory.txt linux-2.4.23-badram/Documentation/memory.txt --- linux-2.4.23/Documentation/memory.txt Fri Nov 9 13:58:02 2001 +++ linux-2.4.23-badram/Documentation/memory.txt Sat Nov 29 10:38:49 2003 @@ -18,6 +18,14 @@ 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. @@ -45,6 +53,8 @@ * Try passing the "mem=4M" option to the kernel to limit Linux to using a very small amount of memory. + If this helps, read /usr/src/linux/Documentation/badram.txt + to learn how to find and circuimvent memory errors. Other tricks: diff -u -r -N linux-2.4.23/arch/i386/config.in linux-2.4.23-badram/arch/i386/config.in --- linux-2.4.23/arch/i386/config.in Fri Nov 28 10:26:19 2003 +++ linux-2.4.23-badram/arch/i386/config.in Sat Nov 29 10:38:49 2003 @@ -344,6 +344,8 @@ source drivers/acpi/Config.in +bool 'Work around bad spots in RAM' CONFIG_BADRAM + endmenu source drivers/mtd/Config.in diff -u -r -N linux-2.4.23/arch/i386/defconfig linux-2.4.23-badram/arch/i386/defconfig --- linux-2.4.23/arch/i386/defconfig Fri Nov 28 10:26:19 2003 +++ linux-2.4.23-badram/arch/i386/defconfig Sat Nov 29 10:38:49 2003 @@ -83,6 +83,7 @@ # CONFIG_EISA is not set # CONFIG_MCA is not set CONFIG_HOTPLUG=y +CONFIG_BADRAM=y # # PCMCIA/CardBus support diff -u -r -N linux-2.4.23/arch/i386/mm/init.c linux-2.4.23-badram/arch/i386/mm/init.c --- linux-2.4.23/arch/i386/mm/init.c Fri Jun 13 07:51:29 2003 +++ linux-2.4.23-badram/arch/i386/mm/init.c Sat Nov 29 10:38:49 2003 @@ -92,7 +92,7 @@ void show_mem(void) { - int i, total = 0, reserved = 0; + int i, total = 0, reserved = 0, badram = 0; int shared = 0, cached = 0; int highmem = 0; @@ -106,6 +106,10 @@ highmem++; if (PageReserved(mem_map+i)) reserved++; +#ifdef CONFIG_BADRAM + if (PageBad(mem_map+1)) + badram++; +#endif else if (PageSwapCache(mem_map+i)) cached++; else if (page_count(mem_map+i)) @@ -114,6 +118,9 @@ 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); printk("%ld pages in page table cache\n",pgtable_cache_size); @@ -447,8 +454,13 @@ } #ifdef CONFIG_HIGHMEM -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, + _Bool *bad) { + *bad = 0; if (!page_is_ram(pfn)) { SetPageReserved(page); return; @@ -462,7 +474,13 @@ ClearPageReserved(page); set_bit(PG_highmem, &page->flags); atomic_set(&page->count, 1); - __free_page(page); +#ifdef CONFIG_BADRAM + if (PageBad(page)) + *bad = 1; + else +#else + __free_page(page); +#endif totalhigh_pages++; } #endif /* CONFIG_HIGHMEM */ @@ -478,10 +496,15 @@ #endif } -static int __init free_pages_init(void) + +/** structure for returning multiple values from free_pages_init() */ +typedef struct { int reserved, bad; } PageCount; + +static PageCount __init free_pages_init(void) { extern int ppro_with_ram_bug(void); int bad_ppro, reservedpages, pfn; + PageCount pages = {0,0}; bad_ppro = ppro_with_ram_bug(); @@ -491,22 +514,31 @@ reservedpages = 0; for (pfn = 0; pfn < max_low_pfn; pfn++) { /* - * Only count reserved RAM pages + * Only count reserved and bad RAM pages */ if (page_is_ram(pfn) && PageReserved(mem_map+pfn)) reservedpages++; +#ifdef CONFIG_BADRAM + if (page_is_ram(pfn) && PageBad(mem_map+pfn)) + pages.bad++; +#endif } #ifdef CONFIG_HIGHMEM - for (pfn = highend_pfn-1; pfn >= highstart_pfn; pfn--) - one_highpage_init((struct page *) (mem_map + pfn), pfn, bad_ppro); + for (pfn = highend_pfn-1; pfn >= highstart_pfn; pfn--) { + _Bool bad; + one_highpage_init((struct page *) (mem_map + pfn), pfn, bad_ppro, &bad); + if (bad) pages.bad++; + } totalram_pages += totalhigh_pages; #endif - return reservedpages; + pages.reserved = reservedpages; + return pages; } void __init mem_init(void) { int codesize, reservedpages, datasize, initsize; + PageCount pages; if (!mem_map) BUG(); @@ -518,12 +550,24 @@ /* clear the zero-page */ memset(empty_zero_page, 0, PAGE_SIZE); - reservedpages = free_pages_init(); + reservedpages = (pages = free_pages_init()).reserved; codesize = (unsigned long) &_etext - (unsigned long) &_text; datasize = (unsigned long) &_edata - (unsigned long) &_etext; initsize = (unsigned long) &__init_end - (unsigned long) &__init_begin; +#ifdef CONFIG_BADRAM + printk(KERN_INFO "Memory: %luk/%luk available (%dk kernel code, %dk reserved, %dk data, %dk init, %ldk highmem, %ldk BadRAM)\n", + (unsigned long) nr_free_pages() << (PAGE_SHIFT-10), + max_mapnr << (PAGE_SHIFT-10), + codesize >> 10, + reservedpages << (PAGE_SHIFT-10), + datasize >> 10, + initsize >> 10, + (unsigned long) (totalhigh_pages << (PAGE_SHIFT-10)), + pages.bad << (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), max_mapnr << (PAGE_SHIFT-10), @@ -533,6 +577,7 @@ initsize >> 10, (unsigned long) (totalhigh_pages << (PAGE_SHIFT-10)) ); +#endif #if CONFIG_X86_PAE if (!cpu_has_pae) diff -u -r -N linux-2.4.23/include/asm-i386/page.h linux-2.4.23-badram/include/asm-i386/page.h --- linux-2.4.23/include/asm-i386/page.h Fri Aug 2 17:39:45 2002 +++ linux-2.4.23-badram/include/asm-i386/page.h Sat Nov 29 10:38:49 2003 @@ -132,6 +132,7 @@ #define __pa(x) ((unsigned long)(x)-PAGE_OFFSET) #define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET)) #define virt_to_page(kaddr) (mem_map + (__pa(kaddr) >> PAGE_SHIFT)) +#define phys_to_page(x) (mem_map + ((unsigned long)(x) >> PAGE_SHIFT)) #define VALID_PAGE(page) ((page - mem_map) < max_mapnr) #define VM_DATA_DEFAULT_FLAGS (VM_READ | VM_WRITE | VM_EXEC | \ diff -u -r -N linux-2.4.23/include/linux/mm.h linux-2.4.23-badram/include/linux/mm.h --- linux-2.4.23/include/linux/mm.h Fri Nov 28 10:26:21 2003 +++ linux-2.4.23-badram/include/linux/mm.h Sat Nov 29 10:38:49 2003 @@ -300,6 +300,7 @@ #define PG_reserved 14 #define PG_launder 15 /* written out by VM pressure.. */ #define PG_fs_1 16 /* Filesystem specific */ +#define PG_badram 17 #ifndef arch_set_page_uptodate #define arch_set_page_uptodate(page) @@ -400,6 +401,9 @@ #define PageSlab(page) test_bit(PG_slab, &(page)->flags) #define PageSetSlab(page) set_bit(PG_slab, &(page)->flags) #define PageClearSlab(page) clear_bit(PG_slab, &(page)->flags) +#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) #define PageReserved(page) test_bit(PG_reserved, &(page)->flags) #define PageActive(page) test_bit(PG_active, &(page)->flags) diff -u -r -N linux-2.4.23/mm/bootmem.c linux-2.4.23-badram/mm/bootmem.c --- linux-2.4.23/mm/bootmem.c Thu Nov 28 15:53:15 2002 +++ linux-2.4.23-badram/mm/bootmem.c Sat Nov 29 10:38:49 2003 @@ -257,8 +257,15 @@ if (!test_bit(i, bdata->node_bootmem_map)) { count++; ClearPageReserved(page); +#ifdef CONFIG_BADRAM + if (!PageBad(page)) { + set_page_count(page, 1); + __free_page(page); + } +#else set_page_count(page, 1); __free_page(page); +#endif } } total += count; @@ -272,8 +279,15 @@ 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); +#ifdef CONFIG_BADRAM + if (!PageBad(page)) { + set_page_count(page, 1); + __free_page(page); + } +#else set_page_count(page, 1); __free_page(page); +#endif } total += count; bdata->node_bootmem_map = NULL; diff -u -r -N linux-2.4.23/mm/page_alloc.c linux-2.4.23-badram/mm/page_alloc.c --- linux-2.4.23/mm/page_alloc.c Fri Nov 28 10:26:21 2003 +++ linux-2.4.23-badram/mm/page_alloc.c Sat Nov 29 10:44:23 2003 @@ -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 */ #include @@ -910,3 +911,93 @@ } __setup("lower_zone_reserve=", setup_lower_zone_reserve); + +#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 ", 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 */ +