Messages in this thread | | | From | "Alexander E. Patrakov" <> | Subject | Re: udev is too slow creating devices | Date | Mon, 20 Sep 2004 08:29:17 +0600 |
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Greg KH wrote: > On Sun, Sep 19, 2004 at 10:00:52PM +0600, Alexander E. Patrakov wrote: > >>OK. The fact is that, when mounting the root filesystem, the kernel can >>(?) definitely say "there is no such device, and it's useless to wait >>for it--so I panic". Is it possible to duplicate this logic in the case >>with udev and modprobe? If so, it should be built into a common place >>(either the kernel or into modprobe), but not into all apps. > > > No, we need to just change the kernel to sit and spin for a while if the > root partition is not found. This is the main problem right now for > booting off of a USB device (or any other "slow" to discover device.) > It's a known kernel issue, and there are patches for 2.4 for this, but > no one has taken the time to update them for 2.6. > > >>Then the "char-major" aliases were always broken, do I understand >>correctly? > > > Yes, for most drivers they are broken. Like sound, usb, and others. > > >>Once we realize that, isn't it the time to mark the >>"Automatic kernel module loading" in the kernel configuration as BROKEN >>or OBSOLETE? > > > Fine with me, I've been wanting to do that for years. Are you willing > to handle the fallout of such a patch though? :)
Many thanks for detailed explanation. And, since char-major aliases don't work with udev anyway, and net-pf aliases are easy to enumerate and preload by parsing /lib/modules/`uname -r`/modules.alias, I think that udev users are ready to handle the fallout of this patch.
>>>With hotplug/udev you *know* that the device node is available when your >>>script in dev.d is called with the appropriate environment variables. >> >>Yes. Now we have a lot of short scriptlets under /etc/dev.d. But I don't >>yet see how these scriptlets interact with each other. > > > What do you mean? What kind of relationship do you need explained about > them?
Implementation of various logical primitives. E.g., I use GPRS and want to start pppd during the boot process (i.e., an always-on link), but after the following things:
1) /dev/ttyS0 has been created 2) /dev/ppp has been created 3) modules for line disciplines and PPP compression have been preloaded (e.g. by grepping modules.alias for tty-ldisc and ppp-compress) and are ready for use by pppd 4) firewall rules have been applied
How to "AND" these things together in a /etc/dev.d scriptlet?
-- Alexander E. Patrakov
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