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From: | Anthony Liguori |
Subject: | Re: [Qemu-devel] How does the QEMU load the binary files bios.bin and vgabios-cirrus.bin? |
Date: | Thu, 07 Apr 2011 14:21:16 -0500 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.14) Gecko/20110223 Lightning/1.0b2 Thunderbird/3.1.8 |
On 04/07/2011 01:44 PM, Gleb Natapov wrote:
KVM doesn't support SMM although that's not because of this. KVM doesn't allow execution of ROM memory which makes it difficult to implement PAM in the way it's intended to be implemented. This makes SMM a bit tricky to make work. Since there's never really been a pressing need to support SMM, to my knowledge, noone has even tried.KVM allows to execute ROM memory (BIOS and option roms run this way). It just makes it indistinguishable from RAM, but read only memory slot support shouldn't be too hard. Why ability to execute ROM memory is needed to support SMM though?
QEMU does the leg work already to support SMM. It doesn't work with KVM because we treat SMM as ROM memory and trap read/write access.
To make it work with KVM, you'd have to hack things around to switch the VGA space to RAM in order to the let the SMM code run. It's not impossible, but that's the main reason it doesn't Just Work.
Regards, Anthony Liguori
-- Gleb.
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