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Re: [Qemu-devel] Re: qemu svn r5281 on FreeBSD - slow usb, vmwarevga, s

From: Anthony Liguori
Subject: Re: [Qemu-devel] Re: qemu svn r5281 on FreeBSD - slow usb, vmwarevga, screen updates... (now updated to r5313)
Date: Tue, 30 Sep 2008 09:51:33 -0500
User-agent: Thunderbird (X11/20080723)

Juergen Lock wrote:
In article <address@hidden> you write:

The one thing that really tripped me up with the whole aio kld-module thing. Perhaps we should detect the presence of the module at run time and disable aio? I assume kldload can only be run as root?
Yes.  Atm the ports print a warning when aio is not loaded:
Yeah, I don't think this is enough. I'd rather see AIO be disabled when modfind("aio") is not available (printing a warning along with that would be fine). A non-privileged user cannot load the aio module so it's not very useful to tell them to load it.

OK so how about the following?  (only tested with a raw image, but if
the way its disabled for OpenBSD works for all of them this should as well.)

 Oh and am I right qemu-img doesn't use aio?  If it actually does we may
want to add the same check there instead of just disabling it.  (I kept it
enabled for qemu-nbd since thats not built on FreeBSD anyway.)

Disabling aio for everyone is not the right thing if posix-aio is broken.

What would be better is in block-raw-posix.c, to have a one type check of modfind() (if we're FreeBSD), and if it fails, set a flag that forces the aio routines to call bdrv_aio_{read,write}_em.


Anthony Liguori

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