2.6.24 vs. 2.6.27/29 (was RE: [Linux-Xtensa] shmat and sigpause failed using LTP on Linux 2.6.24)

Marc Gauthier marc at tensilica.com
Wed Apr 22 10:51:46 PDT 2009


Hi,

Just a note to provide some background on 2.6.24 vs. 2.6.27+
kernels for Xtensa cores.  You have probably noticed that most
Wiki pages on linux-xtensa.org still refer to the 2.6.24 kernel
as being the latest stable one.  It is also the latest for which
we've created a "snapshot" tarball.

At some point early last year, work began in earnest on adding
SMP support for Xtensa.  This development would completely
destabilize the kernel for a while, so was done in a completely
separate tree.  SMP also required much more extensive testing to
find and debug subtle (and not so subtle) issues, and stabilize
to a point where we have reasonable confidence in the port.
Piet recently got it to that point, where it runs for days under
constant LTP testing, without problems.  However, the code base
for it has moved beyond 2.6.24, and is still progressing quickly
as the focus is now on merging all these changes with the latest
kernel and submitting them to kernel.org .  Once this is done and
more testing has been done, we expect to create another 'snapshot'.

Which is why, officially, the latest stable tree may still be
considered to be the 2.6.24 one.  Meanwhile you can get to the
latest 2.6.27 or 2.6.29 SMP trees using git.  If you look at the
home page on www.linux-xtensa.org and follow the GIT link, you'll
see these two trees listed (xtensa-2.6.27-smp and xtensa-2.6.29-smp).

You should be able to clone and pull these trees in the usual
manner with git, using these names instead of xtensa-2.6.24 .
Note that the existing buildroot build instructions might not
match exactly with it.  For example, currently the default kernel
config might be setup for SMP instead of single-processor,
requiring you to change that parameter when doing make menuconfig
on the kernel (hopefully the default gets fixed soon).
There might other differences.  You'll have to try and find out.
Step-by-step instructions will only get updated when things
stabilize a bit more and we create a new snapshot.

Hope that helps,

-Marc


P.S.  Anything opinions expressed by a Tensilica employee mailing to
linux-xtensa.org is their own, not necessarily that of Tensilica.


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