Re: [PATCH RFC] x86: check for and defend against BIOS memory corruption

Hugh Dickins
2008-08-29T10:25:42Z

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> On Fri, 29 Aug 2008, Rafał Miłecki wrote:
>
> Out of current discussion I tried using s2ram on patched kernel (I did
> not try s2ram earlier, my problem was (un)plugging HDMI - some ACPI
> code probably).
>
> Corruption output is quite huge, I attached it to bug report:
> http://bugzilla.kernel.org/show_bug.cgi?id=11237
> http://bugzilla.kernel.org/attachment.cgi?id=17526

Not quite the output we were expecting! I've not got around to trying
it yet, so beware, but I think Jeremy's patch needs the following on top.
Or you may prefer to wait until one of us reports that it is now working
as intended.

--- a/arch/x86/kernel/setup.c 2008-08-29 11:17:16.000000000 +0100
+++ b/arch/x86/kernel/setup.c 2008-08-29 11:19:24.000000000 +0100
@@ -636,11 +636,12 @@ void check_for_bios_corruption(void)
unsigned long *addr = __va(scan_areas[i].addr);
unsigned long size = scan_areas[i].size;

- for(; size; addr++, size--) {
+ for(; size; addr++, size -= sizeof(unsigned long)) {
if (!*addr)
continue;
printk(KERN_ERR "Corrupted low memory at %p (%lx phys) = %08lx\n",
addr, __pa(addr), *addr);
+ *addr = 0;
corruption = 1;
}
}