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

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Message-ID: <20210926150329.GA13506@1wt.eu>
Date:   Sun, 26 Sep 2021 17:03:29 +0200
From:   Willy Tarreau <w@....eu>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Jari Ruusu <jariruusu@...tonmail.com>,
        Salvatore Bonaccorso <carnil@...ian.org>,
        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>,
        Aurelien Jarno <aurelien@...el32.net>
Subject: Re: glibc VETO for kernel version SUBLEVEL >= 255

On Sun, Sep 26, 2021 at 01:39:33PM +0200, Greg Kroah-Hartman wrote:
> On Sun, Sep 26, 2021 at 11:31:20AM +0000, Jari Ruusu wrote:
> > On Sunday, September 26th, 2021 at 14:24, Greg Kroah-Hartman <gregkh@...uxfoundation.org> wrote:
> > > Why use an older kernel tree on this device? Rasbian seems to be on
> > > 4.19.y at the least right now, is there something in those older kernel
> > > trees that you need?
> > 
> > Due to circumstances, I need "smallest possible" kernel with all extra
> > stripped out. 4.9.y kernels are smaller than newer ones.
> 
> Smaller by how much, and what portion grew?  Are we building things into
> the kernel that previously was able to be compiled out?  Or is there
> something new added after 4.9 that adds a huge memory increase?
> 
> Figuring that out would be good as you only have 1 more year for 4.9.y
> to be alive, that's not going to last for forever...

FWIW a situation I faced a few times was trying to put a modern kernel
on a small NAND partition of an older device. Nowadays kernels are really
big. I don't have numbers here but for example I never managed to make a
5.10 fit into the 4 MB partition of an old armv5 device where its 3.4 had
plenty of room. And there isn't a single thing to disable, it looks more
like a systemic growth, probably due to all the stuff we now have to
improve large systems performance and harden everything.

Willy