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Re: [Qemu-devel] pci irq confusion
From: |
M. Warner Losh |
Subject: |
Re: [Qemu-devel] pci irq confusion |
Date: |
Mon, 18 May 2009 11:48:47 -0600 (MDT) |
In message: <address@hidden>
Ed Swierk <address@hidden> writes:
: On Fri, May 15, 2009 at 1:39 AM, Gerd Hoffmann <address@hidden> wrote:
: > Putting the three info sources into a table gives this picture:
: >
: > | qemu | lspci | driver
: > ------------------------+--------+---------+----------
: > 00:01.2 usb | 9 | 9 | 9
: > 00:01.3 acpi | 11 | 9 | 11
: > 00:03.0 xen-platform | 11 | 11 | 11
: > 00:04.0 scsi | 9 | 9 | 9
: > 00:05.0 virtio-blk | 11 | 10 | 10
: > 00:06.0 virtio-baloon | 9 | 9 | 9
: >
: > Note the inconsistencies for acpi and virtio-blk. Where do they come from?
: > Is that normal? Or is that something which needs fixing?
:
: qemu's "info pci" monitor command gets the IRQ value from offset 0x3c
: in the device's PCI config space, which is a useless scratch register.
: Some BIOSes may write to this register the actual IRQ assigned to the
: device, but many don't, and I don't know of any OS that relies on it.
: IMHO this IRQ value is misleading and shouldn't be reported by qemu at
: all.
I know that all the BSDs (and I thought Linux) require the scratch
register to be correct, if it isn't 0xff...
Warner