[lkml]   [2011]   [Jun]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
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


 \ /
  Last update: 2011-06-25 00:19    [W:0.126 / U:2.640 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site