x86: check for and defend against BIOS memory corruption

Some BIOSes have been observed to corrupt memory in the low 64k.  This
change:
 - Reserves all memory which does not have to be in that area, to
   prevent it from being used as general memory by the kernel.  Things
   like the SMP trampoline are still in the memory, however.
 - Clears the reserved memory so we can observe changes to it.
 - Adds a function check_for_bios_corruption() which checks and reports on
   memory becoming unexpectedly non-zero.  Currently it's called in the
   x86 fault handler, and the powermanagement debug output.

Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 5 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 1150444a21ab..df48af505d15 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -360,6 +360,11 @@ and is between 256 and 4096 characters. It is defined in the file
                         Format: <io>,<irq>,<mode>
                         See header of drivers/net/hamradio/baycom_ser_hdx.c.
 
+        bios_corruption_check=0/1 [X86]
+                        Some BIOSes seem to corrupt the first 64k of memory
+                        when doing things like suspend/resume.  Setting this
+                        option will scan the memory looking for corruption.
+
         boot_delay=     Milliseconds to delay each printk during boot.
                         Values larger than 10 seconds (10000) are changed to
                         no delay (0).