linux-kernel - Re: glibc VETO for kernel version SUBLEVEL >= 255

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Date:   Sun, 26 Sep 2021 09:28:58 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Jari Ruusu <jariruusu@...tonmail.com>
Cc:     Sasha Levin <sashal@...nel.org>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, Jiri Slaby <jirislaby@...nel.org>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: glibc VETO for kernel version SUBLEVEL >= 255

On Sun, Sep 26, 2021 at 07:23:33AM +0000, Jari Ruusu wrote:
> Earlier this year there was some discussion about kernel version numbers
> after 4.9.255 and 4.4.255. Problem was 8-bit limitation for SUBLEVEL
> number in stable kernel versions. The fix was to freeze LINUX_VERSION_CODE
> number at x.x.255 and to continue incrementing SUBLEVEL number. Seems
> there are more more fallout from that decision. At least some versions of
> glibc do not play well with larger SUBLEVEL numbers.
> 
> 
> # uname -s -r -m
> Linux 4.9.283-QEMU armv6l
> # apt upgrade
> Reading package lists... Done
> Building dependency tree
> Reading state information... Done
> Calculating upgrade... Done
> The following packages will be upgraded:
>  [SNIP]
> Fetched 145 MB in 1min 57s (1244 kB/s)
> Reading changelogs... Done
> Preconfiguring packages ...
> (Reading database ... 39028 files and directories currently installed.)
> Preparing to unpack .../libc6-dbg_2.28-10+rpt2+rpi1_armhf.deb ...
> Unpacking libc6-dbg:armhf (2.28-10+rpt2+rpi1) over (2.28-10+rpi1) ...
> Preparing to unpack .../libc6-dev_2.28-10+rpt2+rpi1_armhf.deb ...
> Unpacking libc6-dev:armhf (2.28-10+rpt2+rpi1) over (2.28-10+rpi1) ...
> Preparing to unpack .../libc-dev-bin_2.28-10+rpt2+rpi1_armhf.deb ...
> Unpacking libc-dev-bin (2.28-10+rpt2+rpi1) over (2.28-10+rpi1) ...
> Preparing to unpack .../linux-libc-dev_1%3a1.20210831-3~buster_armhf.deb ...
> Unpacking linux-libc-dev:armhf (1:1.20210831-3~buster) over (1:1.20210527-1) ...
> Preparing to unpack .../libc6_2.28-10+rpt2+rpi1_armhf.deb ...
> ERROR: Your kernel version indicates a revision number
> of 255 or greater.  Glibc has a number of built in
> assumptions that this revision number is less than 255.
> If you\'ve built your own kernel, please make sure that any
> custom version numbers are appended to the upstream
> kernel number with a dash or some other delimiter.
> 
> dpkg: error processing archive /var/cache/apt/archives/libc6_2.28-10+rpt2+rpi1_armhf.deb (--unpack):
>  new libc6:armhf package pre-installation script subprocess returned error exit status 1
> Errors were encountered while processing:
>  /var/cache/apt/archives/libc6_2.28-10+rpt2+rpi1_armhf.deb
> E: Sub-process /usr/bin/dpkg returned an error code (1)
> 
> 
> 
> Above upgrade works normally if I edit top level Linux source Makefile to
> say "SUBLEVEL = 0" and re-compile new kernel.
> 
> I am not pointing any fingers here, but it seems that either glibc code or
> stable kernel versioning is messed up.

Are you sure this isn't just a warning coming from a script that apt is
running when trying to install glibc?  Or is this from the glibc package
itself?

And what exactly is it testing?  We fixed the build time detection of
the kernel version here, so you should be able to build glibc properly.

This is the first time we've seen this reported, are people using the
newer kernels on systems that are not using glibc?

thanks,

greg k-h