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diff -pruN a/arch/x86/configs/i386_defconfig b/arch/x86/configs/i386_defconfig
--- a/arch/x86/configs/i386_defconfig 2008-07-13 17:51:29.000000000 -0400
+++ b/arch/x86/configs/i386_defconfig 2008-07-14 13:55:23.000000000 -0400
@@ -198,6 +198,7 @@ CONFIG_DMIID=y
# CONFIG_NOHIGHMEM is not set
CONFIG_HIGHMEM4G=y
# CONFIG_HIGHMEM64G is not set
+CONFIG_BADRAM=y
CONFIG_PAGE_OFFSET=0xC0000000
CONFIG_HIGHMEM=y
CONFIG_ARCH_POPULATES_NODE_MAP=y
diff -pruN a/arch/x86/configs/x86_64_defconfig b/arch/x86/configs/x86_64_defconfig
--- a/arch/x86/configs/x86_64_defconfig 2008-07-13 17:51:29.000000000 -0400
+++ b/arch/x86/configs/x86_64_defconfig 2008-07-14 13:55:23.000000000 -0400
@@ -132,6 +132,7 @@ 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 -pruN a/arch/x86/Kconfig b/arch/x86/Kconfig
--- a/arch/x86/Kconfig 2008-07-13 17:51:29.000000000 -0400
+++ b/arch/x86/Kconfig 2008-07-14 13:55:23.000000000 -0400
@@ -907,6 +907,24 @@ config X86_PAE
has the cost of more pagetable lookup overhead, and also
consumes more pagetable space per process.
+
+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 (EXPERIMENTAL)"
diff -pruN a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
--- a/arch/x86/mm/init_32.c 2008-07-13 17:51:29.000000000 -0400
+++ b/arch/x86/mm/init_32.c 2008-07-14 13:55:23.000000000 -0400
@@ -287,11 +287,16 @@ static void __init permanent_kmaps_init(
pkmap_page_table = pte;
}
-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);
init_page_count(page);
+ if (PageBad(page))
+ *bad=1;
+ else
__free_page(page);
totalhigh_pages++;
} else
@@ -299,16 +304,20 @@ void __init add_one_highpage_init(struct
}
#ifndef CONFIG_NUMA
-static void __init set_highmem_pages_init(int bad_ppro)
+static void __init set_highmem_pages_init(int bad_ppro, int* pbad)
{
- int pfn;
+ int pfn, bad;
for (pfn = highstart_pfn; pfn < highend_pfn; pfn++) {
/*
* Holes under sparsemem might not have no mem_map[]:
*/
- if (pfn_valid(pfn))
- add_one_highpage_init(pfn_to_page(pfn), pfn, bad_ppro);
+ if (pfn_valid(pfn)){
+ add_one_highpage_init(pfn_to_page(pfn), pfn, bad_ppro,
+ &bad);
+ if(bad)
+ (*pbad)++;
+ }
}
totalram_pages += totalhigh_pages;
}
@@ -317,7 +326,7 @@ 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 */
pteval_t __PAGE_KERNEL = _PAGE_KERNEL;
@@ -563,7 +572,8 @@ static struct kcore_list kcore_mem, kcor
void __init mem_init(void)
{
- int codesize, reservedpages, datasize, initsize;
+ int codesize, reservedpages, badpages, datasize, initsize;
+
int tmp, bad_ppro;
#ifdef CONFIG_FLATMEM
@@ -586,14 +596,18 @@ 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;
@@ -602,6 +616,18 @@ void __init mem_init(void)
kclist_add(&kcore_mem, __va(0), max_low_pfn << PAGE_SHIFT);
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",
@@ -613,6 +639,7 @@ void __init mem_init(void)
initsize >> 10,
(unsigned long) (totalhigh_pages << (PAGE_SHIFT-10))
);
+#endif
#if 1 /* double-sanity-check paranoia */
printk(KERN_INFO "virtual kernel memory layout:\n"
diff -pruN a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
--- a/arch/x86/mm/init_64.c 2008-07-13 17:51:29.000000000 -0400
+++ b/arch/x86/mm/init_64.c 2008-07-14 13:55:23.000000000 -0400
@@ -79,7 +79,7 @@ early_param("gbpages", parse_direct_gbpa
void show_mem(void)
{
- long i, total = 0, reserved = 0;
+ long i, total = 0, reserved = 0, badram=0;
long shared = 0, cached = 0;
struct page *page;
pg_data_t *pgdat;
@@ -102,6 +102,8 @@ void show_mem(void)
total++;
if (PageReserved(page))
reserved++;
+ else if (PageBad(page))
+ badram++;
else if (PageSwapCache(page))
cached++;
else if (page_count(page))
@@ -110,6 +112,9 @@ 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 -pruN a/arch/x86/mm/pgtable_32.c b/arch/x86/mm/pgtable_32.c
--- a/arch/x86/mm/pgtable_32.c 2008-07-13 17:51:29.000000000 -0400
+++ b/arch/x86/mm/pgtable_32.c 2008-07-14 13:55:23.000000000 -0400
@@ -22,7 +22,7 @@
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 +43,8 @@ void show_mem(void)
highmem++;
if (PageReserved(page))
reserved++;
+ if (PageBad(page))
+ badram++;
else if (PageSwapCache(page))
cached++;
else if (page_count(page))
@@ -53,6 +55,9 @@ 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 -pruN a/CREDITS b/CREDITS
--- a/CREDITS 2008-07-13 17:51:29.000000000 -0400
+++ b/CREDITS 2008-07-14 13:55:23.000000000 -0400
@@ -2850,6 +2850,16 @@ 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 -pruN a/Documentation/badram.txt b/Documentation/badram.txt
--- a/Documentation/badram.txt 1969-12-31 19:00:00.000000000 -0500
+++ b/Documentation/badram.txt 2008-07-14 13:55:23.000000000 -0400
@@ -0,0 +1,275 @@
+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 x86 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 x86 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 x86 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 x86, 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 -pruN a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
--- a/Documentation/kernel-parameters.txt 2008-07-13 17:51:29.000000000 -0400
+++ b/Documentation/kernel-parameters.txt 2008-07-14 13:55:23.000000000 -0400
@@ -36,6 +36,7 @@ parameter is applicable:
APM Advanced Power Management support is enabled.
AVR32 AVR32 architecture is enabled.
AX25 Appropriate AX.25 support is enabled.
+ BADRAM Support for faulty RAM chips is enabled.
BLACKFIN Blackfin architecture is enabled.
DRM Direct Rendering Management support is enabled.
EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
@@ -325,6 +326,8 @@ and is between 256 and 4096 characters.
autotest [IA64]
+ badram= [BADRAM] Avoid allocating faulty RAM addresses.
+
baycom_epp= [HW,AX25]
Format: <io>,<mode>
diff -pruN a/Documentation/memory.txt b/Documentation/memory.txt
--- a/Documentation/memory.txt 2008-07-13 17:51:29.000000000 -0400
+++ b/Documentation/memory.txt 2008-07-14 13:55:23.000000000 -0400
@@ -18,11 +18,22 @@ 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.
If you use "mem=" on a machine with PCI, consider using "memmap=" to avoid
physical address space collisions.
+If this helps, read Documentation/badram.txt to learn how to
+find and circumvent memory errors.
See the documentation of your boot loader (LILO, loadlin, etc.) about
how to pass options to the kernel.
diff -pruN a/include/asm-x86/page_32.h b/include/asm-x86/page_32.h
--- a/include/asm-x86/page_32.h 2008-07-13 17:51:29.000000000 -0400
+++ b/include/asm-x86/page_32.h 2008-07-14 13:55:23.000000000 -0400
@@ -72,6 +72,8 @@ typedef struct page *pgtable_t;
#define pfn_valid(pfn) ((pfn) < max_mapnr)
#endif /* CONFIG_FLATMEM */
+#define phys_to_page(x) pfn_to_page((unsigned long)(x) >> PAGE_SHIFT)
+
extern int nx_enabled;
/*
diff -pruN a/include/linux/kernel.h b/include/linux/kernel.h
--- a/include/linux/kernel.h 2008-07-13 17:51:29.000000000 -0400
+++ b/include/linux/kernel.h 2008-07-14 13:55:23.000000000 -0400
@@ -174,6 +174,8 @@ extern int vsscanf(const char *, const c
extern int get_option(char **str, int *pint);
extern char *get_options(const char *str, int nints, int *ints);
+extern int get_longoption (char **str, long *plong);
+extern char *get_longoptions(const char *str, int nlongs, long *longs);
extern unsigned long long memparse(char *ptr, char **retptr);
extern int core_kernel_text(unsigned long addr);
diff -pruN a/include/linux/page-flags.h b/include/linux/page-flags.h
--- a/include/linux/page-flags.h 2008-07-13 17:51:29.000000000 -0400
+++ b/include/linux/page-flags.h 2008-07-14 13:55:23.000000000 -0400
@@ -93,6 +93,9 @@ enum pageflags {
PG_mappedtodisk, /* Has blocks allocated on-disk */
PG_reclaim, /* To be reclaimed asap */
PG_buddy, /* Page is free, on buddy lists */
+#ifdef CONFIG_BADRAM
+ PG_badram, /* BadRam page */
+#endif
#ifdef CONFIG_IA64_UNCACHED_ALLOCATOR
PG_uncached, /* Page has been mapped as uncached */
#endif
@@ -101,6 +104,7 @@ enum pageflags {
#ifndef __GENERATING_BOUNDS_H
+
/*
* Macros to create function definitions for page flags
*/
@@ -150,6 +154,7 @@ struct page; /* forward declaration */
PAGEFLAG(Locked, locked) TESTSCFLAG(Locked, locked)
PAGEFLAG(Error, error)
+
PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced)
PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty)
PAGEFLAG(LRU, lru) __CLEARPAGEFLAG(LRU, lru)
@@ -161,6 +166,14 @@ PAGEFLAG(Reserved, reserved) __CLEARPAGE
PAGEFLAG(Private, private) __CLEARPAGEFLAG(Private, private)
__SETPAGEFLAG(Private, private)
+#ifdef CONFIG_BADRAM
+TESTPAGEFLAG(Bad, badram)
+SETPAGEFLAG(Bad, badram)
+TESTSETFLAG(Bad, badram)
+#else
+#define PageBad(page) 0
+#endif
+
/*
* Only test-and-set exist for PG_writeback. The unconditional operators are
* risky: they bypass page accounting.
@@ -173,6 +186,7 @@ PAGEFLAG(MappedToDisk, mappedtodisk)
PAGEFLAG(Reclaim, reclaim) TESTCLEARFLAG(Reclaim, reclaim)
PAGEFLAG(Readahead, reclaim) /* Reminder to do async read-ahead */
+
#ifdef CONFIG_HIGHMEM
/*
* Must use a macro here due to header dependency issues. page_zone() is not
diff -pruN a/lib/cmdline.c b/lib/cmdline.c
--- a/lib/cmdline.c 2008-07-13 17:51:29.000000000 -0400
+++ b/lib/cmdline.c 2008-07-14 13:55:23.000000000 -0400
@@ -114,6 +114,70 @@ 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
@@ -151,3 +215,5 @@ unsigned long long memparse (char *ptr,
EXPORT_SYMBOL(memparse);
EXPORT_SYMBOL(get_option);
EXPORT_SYMBOL(get_options);
+EXPORT_SYMBOL(get_longoption);
+EXPORT_SYMBOL(get_longoptions);
diff -pruN a/mm/bootmem.c b/mm/bootmem.c
--- a/mm/bootmem.c 2008-07-13 17:51:29.000000000 -0400
+++ b/mm/bootmem.c 2008-07-14 13:55:23.000000000 -0400
@@ -386,10 +386,12 @@ static unsigned long __init free_all_boo
pfn = PFN_DOWN(bdata->node_boot_start);
idx = bdata->node_low_pfn - pfn;
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 -pruN a/mm/page_alloc.c b/mm/page_alloc.c
--- a/mm/page_alloc.c 2008-07-13 17:51:29.000000000 -0400
+++ b/mm/page_alloc.c 2008-07-14 13:56:24.000000000 -0400
@@ -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)
*/
@@ -536,9 +537,11 @@ void __free_pages_bootmem(struct page *p
{
if (order == 0) {
__ClearPageReserved(page);
- set_page_count(page, 0);
- set_page_refcounted(page);
+ if(!PageBad(page)){
+ set_page_count(page, 0);
+ set_page_refcounted(page);
__free_page(page);
+ }
} else {
int loop;
@@ -4396,6 +4399,91 @@ 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 (TestSetPageBad (pg))
+ reserve_bootmem (addr, PAGE_SIZE, BOOTMEM_DEFAULT);
+ } 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, (long *) 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 */
+
+
+
+
/* Return a pointer to the bitmap storing bits affecting a block of pages */
static inline unsigned long *get_pageblock_bitmap(struct zone *zone,
unsigned long pfn)
|