Messages in this thread | | | Date | Sat, 26 Jul 2003 09:43:17 -0700 | From | "Randy.Dunlap" <> | Subject | Re: Does sysfs really provides persistent hardware path to devices? |
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On Sat, 26 Jul 2003 20:36:13 +0400 Andrey Borzenkov <arvidjaar@mail.ru> wrote:
| | As far as I can tell sysfs device names include logical bus numbers which | means, if hardware is added or removed it is possible names do change. | | Example: | | /sys/devices/pci0000:00/0000:00:1f.4/usb2/2-2/2-2.1/2-2.1:0/host1/1:0:0:0 | | PCI part reflects bus number. Now this example is trivial in that it is | integrated USB controller so it is unlikely to ever change its number - but | if it were external controller (and even worse with PCI-to-PCI bridge) it is | likely that adding extra card would shift all numbers. | | And USB part of name starts with logical USB bus number i.e. it is obvious | that adding one more USB adapter will definitely change it. | | So apparently I cannot rely on sysfs to get reliable persistent information | about physical location of devices. | | the point is - I want to create aliases that would point to specific slots. | I.e. when I plug USB memory stick in upper slot on front panel I'd like to | always create the same device alias for it.
You'll probably get a barrage of replies...
You want udev + namedev, userspace naming policy. See the recent udev announcements from Greg Kroah-Hartman.
udev/namedev use sysfs device tree info to apply device naming policy.
From Greg's version 0.2 announcement: <quotes> kernel.org/pub/linux/utils/kernel/hotplug/udev-0.2.tar.gz
There's a BitKeeper tree of the latest stuff available at: bk://kernel.bkbits.net/gregkh/udev/
I've also placed the slides from my OLS talk up at: http://www.kroah.com/linux/talks/ols_2003_udev_talk/
The paper which attempts to explain the background of udev, what it does, and where it is going is at: http://archive.linuxsymposium.org/ols2003/Proceedings/All-Reprints/Reprint-Kroah-Hartman-OLS2003.pdf </selected quotes>
There's more in the announcment email. This is still early code, so there's much more to be done on it, but the demo yesterday looked very good.
-- ~Randy | http://developer.osdl.org/rddunlap/ | http://www.xenotime.net/linux/ | For Linux-2.6: http://www.codemonkey.org.uk/post-halloween-2.5.txt or http://lwn.net/Articles/39901/ http://www.kernel.org/pub/linux/kernel/people/rusty/modules/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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