Re: Linux 4.0-rc1 out..

From: Christian Borntraeger
Date: Mon Feb 23 2015 - 10:43:30 EST


Am 23.02.2015 um 04:06 schrieb Linus Torvalds:
> .. let's see how much, if anything, breaks due to the version number.
> Probably less than during the 3.0 timeframe, but I can just imagine
> somebody checking for meaningful versions.
>
> Because the people have spoken, and while most of it was complete
> gibberish, numbers don't lie. People preferred 4.0, and 4.0 it shall
> be. Unless somebody can come up with a good argument against it.

The only argument that I can come up with is "we do not break userspace".
For example there is this "gem" in configure.ac of valgrind:


case "${kernel}" in
2.6.*|3.*)
AC_MSG_RESULT([2.6.x/3.x family (${kernel})])
AC_DEFINE([KERNEL_2_6], 1, [Define to 1 if you're using Linux 2.6.x or Linux 3.x])
;;

2.4.*)
AC_MSG_RESULT([2.4 family (${kernel})])
AC_DEFINE([KERNEL_2_4], 1, [Define to 1 if you're using Linux 2.4.x])
;;

*)
AC_MSG_RESULT([unsupported (${kernel})])
AC_MSG_ERROR([Valgrind works on kernels 2.4, 2.6])
;;
esac


This seems to be historic and unused now in the code base. I will send a
patch to valgrind-devel, that just gets rid of this check, but the check
is in all released versions of valgrind and probably others. I think
we do not care that much about failures when building valgrind on top of
systems running 2.2. If we do, I can certainly add a specific check for
1.*,2.0,2.1,2.2,2.3 that bails out then.


Christian

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