Re: [Xen-devel] Re: [Qemu-devel] [PATCH 5/7] xen: add block device backend driver.

[Samuel Thibault <samuel.thibault@xxxxxxxxxxxxx>]

Gerd Hoffmann, le Tue 05 Aug 2008 13:07:52 +0200, a écrit :
> Samuel Thibault wrote:
> > Gerd Hoffmann, le Tue 05 Aug 2008 08:52:26 +0200, a écrit :
> >>> There is: the info node, which is an OR of the
> >>> VDISK_CDROM/REMOVABLE/READONLY flags.
> >> Who sets that node?  Backend driver or xend?
> > 
> > backend, see linux/driver/xen/blkback/xenbus.c 
> 
> Hmm, ok.
> 
> mode="r" (in backend directory) means readonly, ok.
> device-type="cdrom" (backend dir too) means cdrom, ok.

These are set by xend, i.e. when they come from the config, indeed.

> removable can't be indicated to the backend via xenstore?

Doesn't look like it is possible.  Why would you want to do that?

> btw: Looks like blktap doesn't set any VDISK_* flags?

I guess that's because blktap doesn't have the information.  The "info"
node is information about the underlying source of data, detected by
the block backend, while "mode" and "device-type" are configured by the
user (and should override the "info" information I guess).

Samuel

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