[sane-devel] failing make sane-backends-1.0.18; sanei_scsi question

[Gerhard Jaeger]

On Thursday 18 January 2007 20:55, abel deuring wrote:
[SNIPSNAP]
> GNU C Library stable release version 2.5 (20061011), by Roland

ah - I see pretty new beast ;)

> Compiled on a Linux 2.6.18 system on 2006-11-26.

Hmmm - okay. So they will use these headers...
> 
> >>> Anyway could you guys please try and add the compiler.h only to the 
> >>> HAVE_SCSI_SG_H path?
> >> Well, before making any "real" patch, the first thing I'd like to
> >> know is, if we have a special Suse 10.2 bug, or if something changed
> >> in the kernel headers...
> > 
> > Hmmm - seems we need to check how they compile their glibc and which
> > kernel-headers they use - I think Johannes is around and might could
> > shade some light on that - maybe also on that resmgr stuff.
> 
> I think you spotted the cause in the diff file:

Well, I've only copied the patch from the SuSE srpm ;)

> > BTW: they use the following patch:
> > --- sanei/sanei_scsi.c.orig     2005-04-22 10:36:17.000000000 +0200
> > +++ sanei/sanei_scsi.c  2006-07-04 10:16:49.000000000 +0200
> > @@ -1273,7 +1273,7 @@
> >       disconnect... ;-( */
> >    {
> >      int timeout;
> > -    timeout = sane_scsicmd_timeout * HZ;
> > +    timeout = sane_scsicmd_timeout * sysconf(_SC_CLK_TCK);
> >      ioctl (fd, SG_SET_TIMEOUT, &timeout);
> >    }
> >  #endif
> 
> Seems that the Suse folks did not trust the usage of the HZ macro
> that much. IIRC, HZ gives something like the kernel-internal timer
> resolution or similar, and specifiying this value outside a header
> file make some sense.

Since 2.6, the kernel runs with two timer resolutions, one for the
internal accounting, which is in general 1000Hz -> 1ms and the other
one having a 4ms = 100Hz resolution (the default). The later one is in
general reflected by the HZ, that is used in the scsi lib.
While doing some cross-compilation stuff, I've already seen this
sysconf stuff, so it should be save to use it. Could you please
check the attached patch? (It's borrowed from gdb code)

> Compiling sanei_scsi.c from sane-backends 1.1.18 with this patch
> instead of the added #include line works fine.
> 
That's what I've expected ;)

Gerhard
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