Re: udev event completion order
On Wed, Dec 21, 2005 at 07:29:16PM +0000, Darren Salt wrote:
> I'd call that broken, just as I consider udev (076) to be broken given that
> it breaks expectations wrt device naming. (Here, it swapped the names of the
> DVD drives (drivers are built-in) and sound devices (drivers are modular).)
But that was the case since ages for SCSI (and nowadays SATA) devices.
No modules, no udev, just plug a new SATA/SCSI disk to the controller
that happens to be detected first and all disks on the other controller
gets renamed. udev at least provides persistent naming using
/dev/disk/by-{id,label,path,uuid}.
This is also true for any add-on cards: just plug them to different PCI
slots and the attached devices get renamed. This is not a new problem at
all, it is just exposed more frequently as device handling becomes more
and more dynamic. Again, udev now provides an interface to manually
override these name changes if you want to.
Btw. looking at /usr/src/linux/init/do_mounts.c, the name parsing is
already sysfs-based so it would not be too hard to implement support for
something like
"root=/sys/devices/pci0000:00/0000:00:1e.0/0000:02:0b.2/usb5/5-2/5-2.4/5-2.4:1.0/host0/target0:0:0/0:0:0:0"
So if you worry that the "root=/dev/sda1" style is not
reliable (well, it never was), then talk to the kernel guys.
Gabor
--
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MTA SZTAKI Computer and Automation Research Institute
Hungarian Academy of Sciences
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