[Xen-devel] Re: [PATCH] Introduce dom0-min-space configuration option

[Paolo Bonzini <pbonzini@xxxxxxxxxx>]

On 07/26/2010 01:21 PM, Michal Novotny wrote:
> On 07/26/2010 01:18 PM, Paolo Bonzini wrote:
> > On 07/26/2010 12:36 PM, Michal Novotny wrote:
> > > On 07/26/2010 11:59 AM, Paolo Bonzini wrote:
> > > > On 07/26/2010 08:55 AM, Michal Novotny wrote:
> > > > > Or do you think that we should alter the message in gunzip function to
> > > > > say that there's an error in data stream (premature end of data
> > > > > stream)
> > > > > and that user should check for enough space on dom0?
> > > > No, the gunzip function (in libxc, if I understood the context) should
> > > > not even be called if pygrub could not write the file. Instead, it
> > > > should print something like
> > > >
> > > > pygrub: No space left on device
> > > >
> > > > and exit. There's absolutely no error checking here:
> > > >
> > > > data = fs.open_file(chosencfg["kernel"]).read()
> > > > (tfd, bootcfg["kernel"]) = tempfile.mkstemp(prefix="boot_kernel.",
> > > > dir="/var/run/xend/boot")
> > > > os.write(tfd, data)
> > > > os.close(tfd)
> > > >
> > > > (and likewise for initrd) and that's the bug.
> > > >
> > > > Paolo
> > > Paolo, that's correct but the issue here is that we don't know until we
> > > extract it from image file.
> > os.write would return -1 and set errno to ENOSPC (besides, any other
> > errno should get the same treatment), no?
> Maybe, I need to check the docs first but you're most likely right about
> this. Nevertheless this is the pygrub code AFAIK so some patch for xend
> would be necessary as well, otherwise libvirt-based tools would complain
> with "Boot loader didn't return any data!" message.
That's the least of the problems, if a sensible error message is present 
too.  I agree with Ian, let's first fix the main cause.  Then we can see 
what the fallout is.
Paolo

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