Message-ID: <54EB4A98.6020300@de.ibm.com>
Date: Mon, 23 Feb 2015 16:43:20 +0100
From: Christian Borntraeger <borntraeger@de.ibm.com>
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To: Linus Torvalds <torvalds@linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        jseward@acm.org
Subject: Re: Linux 4.0-rc1 out..
References: <CA+55aFzS==STcTbwabdvw=7_xX08kkUd=g2Q4XbWJzKbpjyN1A@mail.gmail.com>
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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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