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[Qemu-devel] IRQ problems under qemu


From: Tomas Carnecky
Subject: [Qemu-devel] IRQ problems under qemu
Date: Fri, 05 Dec 2008 09:35:21 +0100
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1b3pre) Gecko/20081128 Shredder/3.0b1pre

When I tried to run coreboot under qemu, I was at first positively surprised how well the things worked. The BIOS + linux kernel payload booted in no time! But when I then tried to set up networking, I couldn't get that to work. Somehow the linux kernel couldn't locate the interrupts of the NIC. After some digging I found out that coreboot doesn't provide ACPI tables and instead uses PCI IRQ table (I had to extract this table from a running qemu system using the getpir utility and then copy it to coreboot, if you want that patch, I can send that too). Coreboot copies this table at runtime into memory at 0xf0000. Apparently 0xf0000-0xfffff is part of the ISA BIOS, and qemu marks this range as read-only. The attached patch for qemu fixes that and also cleans up some of the memory initialization. Instead of marking the ISA BIOS as read-only, it copies that part from the BIOS image into the appropriate place (at 0xf0000-0xfffff) and leaves the memory as read-write.

tom

Attachment: cleanup-bios-memory-mapping.patch
Description: Text document


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