Re: 2.6.24-rc1-54866f032307063776b4eff7eadb131d47f9f9b4 fails to boot: kernel BUG at include/linux/scatterlist.h:49!

[Jens Axboe <jens.axboe@oracle.com>]

On Sun, Nov 04 2007, Stefan Richter wrote:
> Jens Axboe wrote:
> > Chained sg lists will only be feed to a scsi host controller that
> > enables chaining in its host template.
> > 
> > The fix looks fine though, it's just not a requirement or bug fix :-)
> 
> Good, then the sbp2 and fw-sbp2 patches can wait for 2.6.25.
> 
> Which criteria decide whether a SCSI low-level driver should enable
> chained s/g lists?  The SBP-2 protocol supports s/g lists with up to
> 65535 entries.  The sbp2 and fw-sbp2 driver limit this currently to SG_ALL.

If the driver can benefit (or even requires) from more segments than you
can typically allocate in one piece, then it should enable chaining. In
general, all drivers must be transitioned to using the sg accessor
helpers, so we can eventually kill the sg chaining enable parameter in
the host template and just make it the default. The parameter is only
there as a transition help.

-- 
Jens Axboe

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