Re: [Qemu-devel] [PATCH 0/4] Add virtio disk identification support

[john cooper <john.cooper@redhat.com>]

Ryan Harper wrote:
> I've applied the qemu and kernel side of this patch series and tested
> this out using the sample code below.  I've also reworked this example
> into a virtioblk_id tool to work with udev to generate /dev/disk/by-id
> links; I'll be submitting a patch set to linux-hotplug with these
> changes, (and update for path_id) and some udev rules to
> persistent-storage script to autogenerate by-id and by-path symlinks for
> virtio-blk devices.

Sorry I didn't respond to you earlier.  Actually the
guest visible interface below was only intended as an
example while waiting for (what I misinterpreted as
Marc's intention to create) a /sys interface.

I'm all for putting this issue to rest, but if we're
going to live with an ioctl interface retrieving the
id string, let's make it a little more friendly from
the user's perspective.  I have a slightly modified
version which basically implements the same interface
but expects the sizeof the entire array to be preset
in the first element.  Otherwise the user has no
way of informing the driver of the destination's size,
nor a way for the driver to indicate when the data
won't fit in the area specified by the user.

I should still have the patch on a test machine which
ATM is unaccessible, but will have at first thing tomorrow.
Let's hold off until then so we can address this nit
and avoid yet another hiccup in nailing down this
interface.

Thanks,

-john

> I've also got a patch to apply ontop of the qemu patches to generate a
> default serial number if one isn't specified (like we do for ide
> devices).
> 
> Anthony, is this series in your queue yet?
> 
> Acked-by: Ryan Harper <ryanh@us.ibm.com>
> 
>>
>>
>> #include <stdio.h>
>> #include <strings.h>
>> #include <sys/types.h>
>> #include <fcntl.h>
>> #include <linux/hdreg.h>
>>
>> #define IOCTL_CMD	'VBID'
>>
>> main()
>> {
>> 	int fd, rv;
>> 	char buf[512];
>>
>> 	bzero(buf, sizeof (buf));
>> 	if ((fd = open("/dev/vda", O_RDONLY)) < 0)
>> 		perror("open");
>> 	else if (ioctl(fd, IOCTL_CMD, buf) < 0)
>> 		perror("ioctl");
>> 	else
>> 		printf("[%s]\n", buf);
>> }
>>
>> -- 
>> john.cooper@redhat.com
>>
> 


-- 
john.cooper@redhat.com