From: Olaf Hering <olaf@aepfle.de>
To: Keir Fraser <keir@xen.org>
Cc: xen-devel@lists.xensource.com
Subject: xenstore index reset in xb_init_comms breaks domU kdump
Date: Wed, 26 Jan 2011 15:00:44 +0100 [thread overview]
Message-ID: <20110126140043.GA27631@aepfle.de> (raw)
Keir,
in the commit below a reset of the rsp_cons/rsp_prod index was added.
http://xenbits.xen.org/staging/xen-unstable.hg?rev/1ec0d322402e
Is this reset really required for save/restore? I have not tried it, but
I would assume a restored guest would get an empty page to work with.
Also:
Could a guest be saved when its in the middle of a xenstore operation?
The reset breaks the xenstore interface in a crashed domU kernel. If the
crash kernel boots, it tries to operate on the new rsp_* index. But this
contains garbage, process_msg() tries to use the data as 'struct
xsd_sockmsg', and kmalloc() fails.
If I remove the rsp_cons/rsp_prod reset in xb_init_comms(), the PV
drivers in the crash kernel can connect to xenstore.
Should the fixup code be removed, or is it essential for save/restore?
Olaf
next reply other threads:[~2011-01-26 14:00 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-26 14:00 Olaf Hering [this message]
2011-01-26 14:21 ` xenstore index reset in xb_init_comms breaks domU kdump Keir Fraser
2011-01-26 14:30 ` Olaf Hering
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