rules: block - add hd to whitelist, need in Xen guest

[robertalks]

Reference bug: http://bugzilla.suse.com/show_bug.cgi?id=954452

[olafhering]

Matching "hd*" will solve the bug.

But I wonder why the on-disk links by-label/by-uuid are tied to specific kernel names. Doesnt this implementation mean that every rule to match other block driver not handled in 60-persistent-storage.rules has to duplicate the label/uuid handling?

Perhaps the label/uuid links should be created unconditionally, then "hd*" does not need to be matched.

[poettering]

Partying like it's 1995, eh? The old /dev/hda drivers are old and undermaintained. Use the newer drivers. If you really want support for /dev/hda, then maintain in downstream, we don't want support for such old stuff that has better replacements in systemd upstream.

[olafhering]

This is not about hardware, but about names. Every block driver is free to pick a name, and xen-blkfront does just that: it picks a name.

@robertalks , please rearrange the code to do the uuid/label symlinks unconditionally.

[poettering]

@olafhering why would it pick names then that conflict with the old IDE hdd drivers?

[olafhering]

@poettering they do not conflict, instead they make the device node provided by PV drivers look like IDE or SCSI to work around system software which does not cope with things it does not know.

In the end the current bug is the lack of by-label and by-uuid symlinks. Something which I think is really unrelated to underlying storage. Thats why I proposed to create these links unconditionally.