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    SubjectRe: the userspace side of driverfs
    > The main ideal that we're shooting for is to have one ASCII value per
    > file. The ASCII part is mandatory, but there will definitely be exceptions
    > where we will have an array of or multiple values per file. We want to
    > minimize those instances, though. Both for the sake of easy parsing, but
    > also for easy formatting within the drivers.

    On IA-64, I've got the arch/ia64/kernel/efivars.c module that exports
    /proc/efi/vars/{NVRAM-variables}. It violates several rules of /proc
    which I'd like to address in 2.5.x via driverfs.
    1) It's in /proc but isn't process-related.
    2) It exports its data as binary, not ascii.

    Proc was chosen because it was simple, didn't require a major/minor
    number, showed easily the set of NVRAM variables that were available
    without needing a separate program to go and query a /dev/efivars file
    to list them; cat and tar are sufficient for making copies of
    variables and restoring them back again. These exact features make
    driverfs make sense too.

    1) is easy to fix. 2) a little less so. The data structure being
    exported is a little over 2KB in length; The data is binary (itself a
    variable length set of structures each with no ascii representation).
    An ascii representation in "%02x" format will be longer than a 4K page
    given to fill out and return. Undoubtedly there's a better way to
    handle this, and I'm open to suggestions. The thing being exported is

    For such cases where the data being exported is really binary,
    having a common set of parse/unparse routines would be nice.


    Matt Domsch
    Sr. Software Engineer, Lead Engineer, Architect
    Dell Linux Solutions
    Linux on Dell mailing lists @
    #1 US Linux Server provider for 2001 and Q1-2/2002! (IDC Aug 2002)

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