From: Kay Sievers <kay.sievers@vrfy.org>
To: linux-hotplug@vger.kernel.org
Subject: Re: Problem in udev with %e device numbering
Date: Sat, 29 Jan 2005 19:53:15 +0000 [thread overview]
Message-ID: <1107028395.15849.21.camel@localhost.localdomain> (raw)
In-Reply-To: <200501291853.30595.gutmann@uni-duesseldorf.de>
On Sat, 2005-01-29 at 18:53 +0100, Michael Gutmann wrote:
> device numbering with %e breaks with NAME{all_partitions} when using
> usb-devices that attach more than one virtual scsi-disk. I've got a
> multi-card-reader that announces itself as four scsi-drives, even if
> no card is plugged in. Partitions certainly can be found only when a
> card is put into the card reader. Unfortunately they are only found if
> something tries to use the card, f.e. fdisk.
If you don't use anything that polls the device for a media change,
which is what all major desktop installation do today, you don't get
these nodes, yes.
> So I have to use NAME(all_partitions}. No problem so far, but I want to
> use symbolic names instead of sd?. But if I use SYMLINK="cardreader%e"
> f.e. there are only links to sd[abcd] and not to the partitions.
> The only way I see is using NAME{all_partitions}="card%e".
There is no sane way to use the %e key in cases you get concurrent
events asking for enumeration of the same name. It's a too simple hack
and there is no way with the current udev model to get this fixed inside
of udev.
The only sane solution, I can imagine would be an external program, that
does the enumeration and returns the value to udev. This external
program would need to maintain its own database in a dotfile in /dev and
must use a file lock to serialize concurrent processes asking for the
value. This topic was already discussed on this list, you may look at
the archives...
Kay
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next prev parent reply other threads:[~2005-01-29 19:53 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-01-29 17:53 Problem in udev with %e device numbering Michael Gutmann
2005-01-29 19:53 ` Kay Sievers [this message]
2005-01-30 10:39 ` Michael Gutmann
2005-01-30 14:58 ` Kay Sievers
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