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

[Michal Novotny <minovotn@redhat.com>]

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?
>
> Paolo
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.

Michal

-- 
Michal Novotny<minovotn@redhat.com>, RHCE
Virtualization Team (xen userspace), Red Hat