From: Jeff Cody <jcody@redhat.com>
To: Kevin Wolf <kwolf@redhat.com>
Cc: amulya.lokesha@emc.com, qemu-devel@nongnu.org,
stefanha@redhat.com, mreitz@redhat.com
Subject: Re: [Qemu-devel] [PATCH] vhdx: Return true for bdrv_has_zero_init
Date: Fri, 5 Dec 2014 09:35:38 -0500 [thread overview]
Message-ID: <20141205143538.GB2433@localhost.localdomain> (raw)
In-Reply-To: <20141205110719.GB6040@noname.str.redhat.com>
On Fri, Dec 05, 2014 at 12:07:19PM +0100, Kevin Wolf wrote:
> Am 05.12.2014 um 11:26 hat Kevin Wolf geschrieben:
> > Like for most other image formats, vhdx images read as all zero in qemu
> > after their creation (we're taking advantage from the fact that qemu has
> > just created the image, because PAYLOAD_BLOCK_NOT_PRESENT actually means
> > undefined rather than zeroed according to the spec).
>
> Brain fart, self-NACK.
>
> This obviously means that 'qemu-img convert' still can't leave zeros in
> the source file unwritten in the destination, otherwise we're corrupting
> data. qemu would still read them correctly, but other implementations
> might not.
>
> We'd have to write the BAT for dynamic images with PAYLOAD_BLOCK_ZERO
> for all clusters before we can make this change.
>
> Jeff, do you want to fix this?
>
Yes, I'll go ahead and put together a patch(es) for that.
next prev parent reply other threads:[~2014-12-05 14:35 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-05 10:26 [Qemu-devel] [PATCH] vhdx: Return true for bdrv_has_zero_init Kevin Wolf
2014-12-05 11:06 ` Max Reitz
2014-12-05 11:07 ` Kevin Wolf
2014-12-05 14:35 ` Jeff Cody [this message]
2014-12-05 11:49 ` Kevin Wolf
2014-12-05 14:34 ` Jeff Cody
2015-10-23 15:32 ` Stefan Hajnoczi
2015-10-23 16:00 ` Kevin Wolf
2015-10-26 10:43 ` Stefan Hajnoczi
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