[Qemu-devel] Xen patches - status summary

[Ian Jackson]

I don't know about you but I'm starting to lose track of all the
patches we're submitting from the Xen tree.  So here's a summary of
recent activity:

Patches from Stefano Stabellini awaiting commit to qemu:

 [1/3] vnc dynamic resolution   } minor discussion, all issues resolved
 [2/3] WMVi extension support   }  so should IMO be applied (updated version
 [3/3] vga shared buffer        }  in case of vga shared buffer patch)
 sdl shared buffer support        no discussion, should be applied IMO
 opengl rendering in the sdl ...  no discussion, should be applied IMO

Patches from me awaiting commit to qemu:

 Use fd signal trick to ... select      discussed, should be applied[1]
 Introduce #define QEMU_ASYNC_EVENTLOOP discussed, should be applied[1]
 usb-linux.c: #define __user ...        discussed, should be applied[2]
 IDE error checking (2 patches)         2nd repost, should be applied[3]

Patches from me currently in discussion / awaiting rework:

 wrap up use of dangerous ctype.h ...   rework suggested by Anthony
 IDE write cache (3 patches)            2nd repost, under discussion[4]

Recent patches from me no longer needing attention:

 suppress ... warnings in scsi-generic  applied, thanks
 Do not try to use -net user as ...     applied, thanks
 Check that ... submission succeeds     superseded by `IDE error ...'

Looking at my git logs here there are quite a few more which will be
forthcoming but perhaps it would be good to digest these first ?

Thanks,
Ian.

Discussion:

[1] Re: Use fd signal trick to break us out of select
    Re: Introduce #define QEMU_ASYNC_EVENTLOOP

Anthony Ligouri had a different patch based on a helper thread to
provide an emulation of signalfd rather than use of a signal handler.
However (as confirmed by Jamie Lokier) some versions of glibc have
a bug in the handling of the glibc internal aio helper thread(s)
which can make efforts to block signals ineffective.  This means
that Anthony's patch will not work properly on those libcs and as
I wrote already this means that my patch should be applied.

The QEMU_ASYNC_EVENTLOOP change is a tidying up of the NBD feature to
make qemu-nbd share more commonality with qemu-img.  As discussed
there are perhaps even more cleanups that could be done to improve
this but as I say this change is a good start and should be applied.

[2] Re: usb-linux.c: #define __user to work around broken Linux headers

Thiemo Seufer complained that `distros should fix their broken
headers instead', which as I said is I think a ridiculous argument.
The headers have indeed been fixed in most upstreams but we would like
to be portable to older unfixed systems.  No-one else has commented.

[3] Re: IDE error checking

I summarised the discussion in my message `[REPOST] [PATCH 0/2]'.
There has been no recent response.  For the reasons I explain, I think
this patch should be applied now without waiting for any
ENOSPC-auto-pause feature.  Daniel Berrange appeared to agree last
time this was discussed.

This has been previously discussed in February 2008; a less complete
version of the same patch was posted by Samuel Thibault in early
August 2008 and withdrawn in favour of this patchset.

[4] Re: IDE write cache

This is tangentially related to Andrea Arcangeli's comments about IDE
write cacheing; a similar discussion was had about this patch
previously.

This patch has been previously submitted in February 2008 and again in
late March and early April 2008.

If Andrea's comments are justified then a change to qemu is needed
anyway and that could most fruitfully be made on top of this patchset.
So for this reason, and the others I have given, I think this should
be applied now but I appreciate that people might want to wait for the
discussion to settle.

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