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    SubjectRe: [RFC] Don't use linux/version.h anymore to indicate a per-driver version - Was: Re: [PATCH 03/37] Remove unneeded version.h includes from include/
    Em 24-06-2011 18:04, Andy Walls escreveu:
    > On Fri, 2011-06-24 at 14:48 -0400, Devin Heitmueller wrote:
    >> On Fri, Jun 24, 2011 at 2:34 PM, Stefan Richter
    >> <> wrote:
    >>> If the "driver version" is in fact an ABI version, then the driver author
    >>> should really increase it only when ABI behavior is changed (and only if
    >>> the behavior change can only be communicated by version number --- e.g.
    >>> addition of an ioctl is not among such reasons). And the author should
    >>> commit behavior changing implementation and version number change in a
    >>> single changeset.
    >>> And anybody who backmerges such an ABI behavior change into another kernel
    >>> branch (stable, longterm, distro...) must backmerge the associated version
    >>> number change too.
    >>> Of course sometimes people realize this only after the fact. Or driver
    >>> authors don't have a clear understanding of ABI versioning to begin with.
    >>> I am saying so because I had to learn it too; I certainly wasn't born
    >>> with an instinct knowledge how to do it properly.
    >>> (Disclaimer: I have no stake in drivers/media/ ABIs. But I am involved
    >>> in maintaining a userspace ABI elsewhere in drivers/firewire/, and one of
    >>> the userspace libraries that use this ABI.)
    >> Hi Stefan,
    >> To be clear, I don't think anyone is actually proposing that the
    >> driver version number really be used as any form of formal "ABI
    >> versioning" scheme. In almost all cases, it's so the application can
    >> know to *not* do something is the driver is older than X.
    > MythTV, for example, used to use the driver version to work around old
    > VBI bugs and MPEG encoder quirks that the older version of the driver
    > may not have known how to handle:
    > But for newer versions, MythTV could avoid using its own odd hacks.
    > The bleeding edge MythTV now has most of these removed.

    Removing it is a good thing.

    >> Really, this is all about applications being able to jam a hack into
    >> their code that translates to "don't call this ioctl() with some
    >> particular argument if it's driver W less than version X, because the
    >> driver had a bug that is likely to panic the guy's PC".
    > Well, not even panics per se, but some thing like the VBI is broken, or
    > the volume control doesn't work, IR blaster is works for this version,
    > or something else stupid that is very visible to the end user.
    > I also use the driver version for troubleshooting problem with users. I
    > roughly know what wasn't working in what version of the cx18 and ivtv
    > drivers. If the end user can tell me the driver version (using v4l2-ctl
    > --log-status) along with his symptoms, it makes my life easier. Being
    > able to efficiently help the end user is a win for both me and the end
    > user.

    If you add it to MODULE_VERSION, you can get the version with:

    $ modinfo -F version vivi


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