Re: Reading /dev/mem by dd

From: Cyrill Gorcunov
Date: Thu Nov 12 2009 - 16:29:48 EST


On Thu, Nov 12, 2009 at 10:07:22PM +0100, Krzysztof Halasa wrote:
> "Henrique de Moraes Holschuh" <hmh@xxxxxxxxxx> writes:
>
> > In this case, the problem seems to be access over /dev/mem to stuff the
> > kernel is already taking care of.
>
> Not sure if local APIC counts as "PCI space and the BIOS code and data
> regions" but:
>
> $ grep STRICT_DEVMEM -A 15 arch/x86/Kconfig.debug
> config STRICT_DEVMEM
> bool "Filter access to /dev/mem"
> ---help---
>

Yes, having this option turned on an access to LAPIC/IO_APIC
space will be forbidden.

-- Cyrill
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