On 11/11/2013 03:35 AM, Ingo Molnar wrote:
>
> If we reserve everything in low memory, all the time (which I very much
> argue we should do) then the checker becomes a no-op and can be removed.
>
Oops! I had misunderstood how the checker worked -- I thought it
checked the *reserved* memory, but it in fact reserves memory
*independently* and then checks it.
The problem is fundamentally that setup_bios_corruption_check(); is
called too early in setup_arch() -- quite possibly due to other code
movement around it:
#ifdef CONFIG_X86_CHECK_BIOS_CORRUPTION
setup_bios_corruption_check();
#endif
reserve_real_mode();
trim_platform_memory_ranges();
trim_low_memory_range();
init_mem_mapping();
setup_bios_corruption_check() should presumably be called between
trim_low_memory_range() and init_mem_mapping(). I'm actually surprised
that we don't trip on this *all the time* since the realmode trampoline
falls in this area...
At the same time, we should change the default for
CONFIG_X86_RESERVE_LOW to 640, and perhaps move it under EXPERT.
What do you guys think?
-hpa
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