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Re: [Qemu-devel] [RFC PATCH] msix: Support specifying offsets, BARs, and
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] [RFC PATCH] msix: Support specifying offsets, BARs, and capability location |
Date: |
Sun, 10 Jun 2012 19:15:42 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
On 2012-06-10 19:02, Alex Williamson wrote:
> msix_init has very little configurability as to how it lays out
> MSI/X for a device. It claims to resize BARs, but doesn't
> actually do this anymore. This patch allows MSI/X to be fully
> specified, which is necessary both for emulated devices trying
> to match the physical layout of a hardware device as well as for
> any kind of device assignment.
>
> The original intent of msix_init seems to have been to allow
> completely virtual devices so enable MSI/X without knowing
> anything about it. A sort of "here's a BAR and a device, add
> MSI/X to it". We've already dropped the resize support with
> the memory API, and I think it makes sense to tune the interface
> to something that still makes it easy for virtual devices to use,
> but allows the full specification for realistically creating
> emulated devices using MSI/X.
>
> Signed-off-by: Alex Williamson <address@hidden>
> ---
>
> This needs more testing, but I wanted to send it out in case someone
> else is working on something similar. In order to not modify the
> generic capability adding code VFIO needs to tell qemu about ever
> capability for a device. The main roadblock to doing that is that
> msix_init does not provide sufficient specification of the MSI/X area
> to match a physical device. This solves that.
Reminds me that you asked for my version:
http://git.kiszka.org/?p=qemu.git;a=shortlog;h=refs/heads/queues/msi
specifically the top two commits. WIP, just picked the old commits,
result untested.
Still need to look into your version.
Jan
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