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    SubjectRe: devfs and /proc/ide/hda
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    >>>>> " " == AJ Lewis <lewis@sistina.com> writes:

    > On Wed, Feb 28, 2001 at 04:10:23PM +0100, Guest section DW
    > wrote:
    >> On Wed, Feb 28, 2001 at 08:52:54PM +1100, Glenn McGrath wrote:
    >>
    >> > Im running kernel 2.4.1, I have entries like /proc/ide/hda, >
    >> /proc/ide/ide0/hda etc irrespective of wether im using devfs or
    >> > traditional device names. > > Is always using traditional
    >> device names for /proc/ide intentional, or > is it something
    >> nobody has gotten around to fixing yet?
    >>
    >> If only humans look at /proc, and they like typing long names,
    >> then there is no objection against changing /proc. As it is,
    >> however, quite a few programs look at /proc for information
    >> about devices. I don't think it would be a good idea to "fix"
    >> /proc and simultaneously break all these programs.

    > What it should do is change based on whether devfs is mounted
    > or not. It doesn't make *any* sense to have
    > /dev/ide/host0/foo/bar in your /proc/partitions entries if you
    > aren't mounting devfs. The /proc/partitions entry is the only
    > way I know of for something like LVM to determine which devices
    > to scan for Volume Groups. If you can't read /proc/partitions,
    > it has to attempt to scan all block devices it recognizes,
    > regardless of whether they are actually on the system or not.
    > This can take several minutes.

    First:

    % cat /proc/partitions
    major minor #blocks name

    3 0 20010816 ide/host0/bus0/target0/lun0/disc
    3 1 192748 ide/host0/bus0/target0/lun0/part1
    3 2 249007 ide/host0/bus0/target0/lun0/part2
    3 3 1 ide/host0/bus0/target0/lun0/part3
    3 5 289138 ide/host0/bus0/target0/lun0/part5
    3 6 1951866 ide/host0/bus0/target0/lun0/part6
    3 7 979933 ide/host0/bus0/target0/lun0/part7
    3 8 16346106 ide/host0/bus0/target0/lun0/part8
    33 0 80043264 ide/host2/bus0/target0/lun0/disc
    33 1 80035798 ide/host2/bus0/target0/lun0/part1

    So its already right.

    Secondly with devfs, why not just scan all /dev/discs/?

    % ls -l /dev/discs
    total 0
    lr-xr-xr-x 1 root root 30 Jan 1 1970 disc0 -> ../ide/host0/bus0/target0/lun0/
    lr-xr-xr-x 1 root root 30 Jan 1 1970 disc1 -> ../ide/host2/bus0/target0/lun0/

    Also if lvm opens all known devices by way of /dev/whatever while
    scanning, it will only find existing devices there with devfs.

    MfG
    Goswin
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