Re: [PATCH] Fix devmem_is_allowed for below 1MB accesses for anefi machine

[Matthew Garrett]

On Tue, Oct 02, 2012 at 02:50:09PM -0700, H. Peter Anvin wrote:

> That sounds like exactly the opposite of normal /dev/mem behavior... we
> allow access to non-memory resources (which really could do anything if
> misused), but not memory.

>From arch/x86/mm/init.c:

 * On x86, access has to be given to the first megabyte of ram because that area
 * contains bios code and data regions used by X and dosemu and similar apps.

Limiting this to just RAM would be safer than it currently is. I'm not 
convinced that there's any good reason to allow *any* access down there 
for EFI systems, though.

-- 
Matthew Garrett | mjg59@xxxxxxxxxxxxx
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