Messages in this thread | | | Date | Wed, 3 Oct 2012 05:31:17 +0100 | From | Matthew Garrett <> | Subject | Re: [PATCH] Fix devmem_is_allowed for below 1MB accesses for an efi machine |
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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@srcf.ucam.org
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