From: Stefan Hajnoczi <stefanha@gmail.com>
To: Markus Armbruster <armbru@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Fam Zheng <famz@redhat.com>,
qemu-trivial@nongnu.org, Michael Tokarev <mjt@tls.msk.ru>,
qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>,
Arthur Gautier <baloo@gandi.net>
Subject: Re: [Qemu-devel] [Qemu-trivial] [PATCH] vmdk: Fix cylinders number during convert
Date: Tue, 28 Oct 2014 16:00:41 +0000 [thread overview]
Message-ID: <20141028160041.GA3969@stefanha-thinkpad.redhat.com> (raw)
In-Reply-To: <87egtzusaa.fsf@blackfin.pond.sub.org>
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On Thu, Oct 23, 2014 at 10:03:25AM +0200, Markus Armbruster wrote:
> Michael Tokarev <mjt@tls.msk.ru> writes:
>
> > On 10/22/2014 05:25 PM, Arthur Gautier wrote:
> >> We can not rely on int cast to get a correct number of cylinders. The
> >> cylinders information was wrong in 49.9999% of cases.
> >>
> >> This ensures the cylinders always gets the ceiling value.
> >
> > Good thing, especially the good probability :), and also a good patch
> > which comes with a test.
> >
> > But I wonder if anything can break this way? Migration, windows guest
> > being unable to find its partitions, something else?
> >
> > And more. What-if our drive size in cylinders will be larger than
> > the size in bytes? The proposed div_round_up() will increase number
> > of cylinders, so size in CHS will be larger than size in bytes. Maybe
> > there was a reason why originally the size in cylinders was calculated
> > by truncating extra fractional part? What-if guest will try to access
> > the very last CHS which is incomplete?
>
> Too many questions for -trivial, copying VMDK maintainers.
Fam: What do you think about this change?
Stefan
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next prev parent reply other threads:[~2014-10-28 16:01 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-22 13:25 [Qemu-devel] [PATCH] vmdk: Fix cylinders number during convert Arthur Gautier
2014-10-23 6:55 ` [Qemu-devel] [Qemu-trivial] " Michael Tokarev
2014-10-23 8:03 ` Markus Armbruster
2014-10-28 16:00 ` Stefan Hajnoczi [this message]
2014-10-29 1:28 ` Fam Zheng
2014-10-30 9:09 ` Arthur Gautier
2014-10-30 10:27 ` Fam Zheng
2014-10-30 14:28 ` Arthur Gautier
2014-10-31 2:52 ` Fam Zheng
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