Re: [Qemu-devel] [PATCH] bdrv_flush error handling

["Daniel P. Berrange" <berrange@redhat.com>]

On Thu, Feb 21, 2008 at 11:28:23AM -0600, risc@volumehost.com wrote:
> On Thu, Feb 21, 2008 at 05:24:10PM +0000, Daniel P. Berrange wrote:
> > On Thu, Feb 21, 2008 at 12:19:22PM -0500, Ben Taylor wrote:
> > > > > Also, in block-raw-posix.c, raw_pwrite et al seem to return -1 on
> > > > > error (the return value from write) whereas the other block read/write
> > > > > methods return errno values.  This is a mistake, surely ?  -1 would be
> > > > > -EPERM.  If any of the callers did anything with these return values
> > > > > you'd get incorrect error indications.
> > > > > 
> > > > > 
> > > > > Finally, it would perhaps be best if the block device emulators wrote
> > > > > to the qemu console to complain if they give write errors.  Otherwise
> > > > > the errno value and other important information will be lost, which
> > > > > makes debugging hard.
> > > > 
> > > > If by 'qemu console' you mean stderr, then fine, but please don't
> > > > spew log messages to the  monitor console, because that'll make it
> > > > very hard to interact with reliably from management tools. 
> > > 
> > > Would it make sense to have a log messages screen associated with
> > > the monitor (like Ctrl-Alt-7) to deal with those sorts of things?
> > 
> > Why invent a new special QEMU log screen, when stderr works just fine. If an
> > app wants to capture log messages they just capture stderr and persist it.
> > We already capture stderr for exactly this reason in libvirt when managing
> > QEMU instances.
> 
> Please excuse my intrusion in this thread, but I'm a user of the new
> ncurses user interface. when ssh'd in, running qemu, I don't believe 
> having messages pop out of stderr and over the current screen contents is 
> the appropriate behavior, as it sounds to me like it would cause redraw 
> defects in the normal text console (via ncurses)

So just redirect stderr to a logfile, or /dev/null, etc, etc

Dan.
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