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    SubjectRe: [patch] IBM HDAPS accelerometer driver.


    On Mon, 29 Aug 2005, Pavel Machek wrote:

    > Hi!
    >
    > > >>I think he doesn't need to export it at all and he should write code to
    > > >>park and disable hard disk instead.
    > > >>(in userspace it's unsolvable --- i.e. you can't enable hard disk when
    > > >>detected stable condition if the daemon is swapped out on that hard disk)
    > > >
    > > >man mlockall() :-).
    > >
    > > You also must not use any syscall that allocates even temporary memory in
    > > kernel (select, poll, many others ...) or that waits on semaphore that
    > > might be held while allocating memory (i.e. audit and rewrite ide ioctl
    > > path).
    >
    > Kernel module would have exactly same problem.

    It has control of its memory allocations.

    > > And you need extra flags to protect the daemon from being killed at
    > > shutdown or blocked at suspend.
    >
    > Why?

    Because the disk must be unlocked even if the laptop falls down while
    a suspension or shutdown are under way.
    And it should work until the heads are parked anyway.

    Regards
    Oliver

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