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    SubjectRe: [PATCH v3] mmc: add config and runtime option for number of mmcblk minors
    On Wed, Sep 8, 2010 at 8:57 AM, Olof Johansson <> wrote:
    > On Wed, Sep 08, 2010 at 05:19:25PM +0200, Kay Sievers wrote:
    >> On Wed, Sep 8, 2010 at 16:57, Olof Johansson <> wrote:
    >> > On Wed, Sep 08, 2010 at 10:25:58PM +0800, Lei Wen wrote:
    >> >
    >> >> The patch's purpose is good. As modern sd&mmc is used to host the file
    >> >> system, the 8 partition limitation is becoming a kind of bottleneck...
    >> >> But why not just add GENHD_FL_EXT_DEVT flag to allow mmc use extended
    >> >> partition numbers?
    >> >
    >> > No need to quote the whole patch next time. :)
    >> >
    >> > Given that MMC is sometimes used in deeply embedded environments where
    >> > udev might not be running to take care of dynamic device numbering,
    >> > I chose to stay with a static layout.
    >> >
    >> > I could be convinced otherwise though. It would cause some additional
    >> > hassles for me since we start udev lateish during boot and have a
    >> > prepopulated /dev before that, but that can be dealt with.
    >> I think the extended number are only used for stuff larger than the static 8?
    > Ah, yes, of course.
    >> Apart from that, you can not reliably or securely use a static /dev
    >> these days, you never know which device you talk to, because the
    >> kernel has far too many dynamically assigned numbers. For that reason,
    >> most embedded setups use the busybox hack to populate /dev. Recent
    >> kernels have a devfs again, and there is no reason today to continue
    >> any static /dev experiments -- unless someone is going over the entire
    >> tree and fixes all the dynamic assignments, which is unlikely to
    >> happen ever.
    > Yeah, it's a weak argument but I wanted to go for the least surprising
    > one for anyone who still relies on static numbering of mmc, since it's
    > used as root device, etc.
    > But with the first 8 minors being the same as before, there's little
    > reason to care about that -- the EXT_DEVT approach will actually be
    > the smaller change, since it won't renumber anything, just extend in a
    > different part of the address space.
    > Lei, want to submit a proper patch for it to replace mine?

    I have a tested patch for this. It also cleans up the connection
    between devidx and minor numbers. I'll send it shortly.

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      Last update: 2010-09-08 18:51    [W:0.023 / U:58.040 seconds]
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