On 3/2/21 7:40 AM, Thanos Makatos wrote:
-----Original Message-----
From: Daniel Henrique Barboza <danielhb413@xxxxxxxxx>
Sent: 01 March 2021 18:07
To: Peter Krempa <pkrempa@xxxxxxxxxx>; Thanos Makatos
<thanos.makatos@xxxxxxxxxxx>
Cc: libvir-list@xxxxxxxxxx
Subject: Re: using libvirt 4.5 with upstream qemu
On 3/1/21 12:47 PM, Peter Krempa wrote:
On Mon, Mar 01, 2021 at 15:30:58 +0000, Thanos Makatos wrote:
I'm trying to use QEMU master with libvirt 4.5 and QEMU seems to be
hanging when I try to start a guest.
My environment is a modified CentOS 7.9 installation using libvirt
4.5.0. When I use a modified version of QEMU 2.12 (reasonably close
to the stock CentOS
version) everything works fine. When I try to use a fairly recent
version of QEMU (e.g. v5.2.0-729-g89ff714f4b).
qemu 118657 1.6 0.0 0 0 ? Z 14:50 0:00 [qemu-kvm]
<defunct>
qemu 118664 0.0 0.0 207340 3560 ? Ssl 14:50 0:00
/usr/libexec/qemu-kvm -S -no-user-config -nodefaults -nographic -machine
none,accel=kvm:tcg -qmp
unix:/var/lib/libvirt/qemu/capabilities.monitor.sock,server,nowait -pidfile
/var/lib/libvirt/qemu/capabilities.pidfile -daemonize
qemu 118666 0.0 0.0 275008 13916 ? Sl 14:50 0:00
/usr/libexec/qemu-kvm -S -no-user-config -nodefaults -nographic -machine
none,accel=kvm:tcg -qmp
unix:/var/lib/libvirt/qemu/capabilities.monitor.sock,server,nowait -pidfile
/var/lib/libvirt/qemu/capabilities.pidfile -daemonize
These are possibly a leftover from libvirt's capability probing. I
recall that we had some issue with capability detection qemu instances
getting stuck but I don't remember the details any more.
Not sure if related to this reported problem, but upstream QEMU when
compiled with the trace backend was having problems daemonizing. I
experienced a similar issue in the start of the year when running upstream
Libvirt with upstream QEMU.
I posted a patch fixing it in QEMU [1] but it wasn't pushed as of today.
I am not sure if the problem was fixed in another way or if the patch I posted
ended up left behind.
Thanos, if you're compiling QEMU with a trace backend (e.g. with --enable-
trace-backend= in ../configure) it might be worth compiling it without this
option. There is a chance you're hitting same problem I mentioned above.
Thanks Daniel, removing --enable-trace-backend did fix the issue!
Glad I could help. Thanks for checking it out.
Guess I'll ping the QEMU mailing list about the fix I posted. Seems like the
daemonization is still broken upstream with the trace backend enabled.
DHB
