Re: [RFC PATCH] Multi-threaded device probing

Matthew Wilcox
2006-07-26T16:42:37Z

On Wed, Jul 26, 2006 at 09:16:47AM -0700, Greg KH wrote:
> However, almost all distros now use persistant names for network devices
> due to the PCI Hotplug issue, so it isn't probably as bad as you might
> think.

Oh, for people using a distro, I'm sure it's no problem at all. It's
the homebrew people I'm worried about ;-)

> > I still think we need a method of renaming block devices, but haven't
> > looked into it in enough detail yet.
>
> That could get "interesting"...
>
> But now that we all are using /dev/disk/ and it has persistant device
> names for block devices, I really don't think it's that big of a deal.

Actually, that's exactly why it's a big deal. The kernel spits out
messages like:

printk(KERN_DEBUG "%s: Mode Sense: %02x %02x %02x %02x\n",
diskname, buffer[0], buffer[1], buffer[2], buffer[3]);

where diskname is something like sda. Now the user has to figure out
what sda means in terms of /dev/disk/ and in terms of scsi h:c:t:l and
in terms of which sticky label is on which drive. If we let userspace
change the gendev's disk_name, that printk can be meaningful to the user
in at least one of those senses.