Re: getting usb mass storage to finish before running init?

From: Nick Bartos (spam99_at_2thebatcave.com)
Date: 02/13/04

  • Next message: Meelis Roos: "Re: Strange atkbd messages with missing keyboard" 
    Date:	Fri, 13 Feb 2004 06:56:57 -0600 (CST)
To: der.eremit@email.de

    I realized that in my config only the flash disk has 2 partitions (the
    rest will only ever have one), so what I will do is keep looking every
    second in /proc/partitions for a disk that has a second partitions, then
    if I find any, I will go through and use tune2fs to check the label on it
    and make sure it matches the one I am looking for (just in case for some
    reason there is another disk in there with a second partition). If I
    don't find a match by a certain timeout period, I will exit with a
    critical error. Since I don't think that any of these systems will have
    more than one disk I will need to run tune2fs on, I won't keep track of
    scanned devices. If that changes I can always tweek the code.

    This isn't as elegant as I wanted, but it should be reliable since I would
    be waiting on something that directly tells me that the flash device is
    ready to go, instead of only waiting an arbitrary amount of time.

    > On Thu, 12 Feb 2004, Nick Bartos wrote:
    >
    >> well, the root filesystem is an initrd, so I can't do that.
    >
    > Then I mean look for the filesystem you want to mount.
    >
    >> I suppose I could compile in the extra info for /proc/partitions and see
    >> if that gives me anything I can keep looking for (don't know if it puts
    >> file system labels in there, but that is probably what I would have to
    >> go
    >> on since that is really the only thing that is constant on all systems).
    >
    > Well, if you know what filesystem type is wanted you could just attempt
    > to mount all the partitions from /proc/partitions with that type
    > (read-only) and look for a unique file - if it's there, keep the fs
    > mounted, otherwise umount and try next candidate.
    >
    > That's basically what I do in an initrd I wrote for CD-ROM booting, I'm
    > just trying to mount iso9660 filesystems and look for /etc/rc.d/rc.cdrom
    > when it succeeds. Better ways to identifiy a block device exist, I'm
    > sure, but the approach works for me. I'm narrowing down the search by
    > scanning the dmesg buffer for ATAPI and SCSI CD-ROM detection messages,
    > but that approach doesn't work for your problem (and is also fragile
    > when using it across several kernel versions).
    >
    >> Is there a quick/clean way to query a device and get the label?
    >
    > findfs from the e2fsprogs package, maybe.
    >
    >> I suppose
    >> I could use tune2fs or something, but I didn't know if there is anything
    >> better/simpler. I don't know if I like the idea of running tune2fs on
    >> each partition again and again. I guess I could keep a list in memory
    >> and
    >> only check each one once, but that is getting a bit more complicated &
    >> time consuming.
    >
    > Well, it's read-only access, so I don't see a problem even with running
    > it multiple times on the same device. Keeping a list of already tried
    > devices isn't black magic, though.
    >
    > --
    > Ciao,
    > Pascal
    > -
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  • Next message: Meelis Roos: "Re: Strange atkbd messages with missing keyboard"

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