From: Tony Battersby <tonyb@cybernetics.com>
To: Jiri Slaby <jirislaby@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org,
Jari Ruusu <jariruusu@protonmail.com>,
David Laight <David.Laight@ACULAB.COM>,
Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de>
Subject: Re: Kernel version numbers after 4.9.255 and 4.4.255
Date: Fri, 5 Feb 2021 12:31:05 -0500 [thread overview]
Message-ID: <0b12bac9-1b4e-ec4a-8a45-5eb3f1dbbeca@cybernetics.com> (raw)
In-Reply-To: <a85b7749-38b2-8ce9-c15a-8acb9a54c5b5@kernel.org>
On 2/4/21 6:00 AM, Jiri Slaby wrote:
> Agreed. But currently, sublevel won't "wrap", it will "overflow" to
> patchlevel. And that might be a problem. So we might need to update the
> header generation using e.g. "sublevel & 0xff" (wrap around) or
> "sublevel > 255 : 255 : sublevel" (be monotonic and get stuck at 255).
>
> In both LINUX_VERSION_CODE generation and KERNEL_VERSION proper.
My preference would be to be monotonic and get stuck at 255 to avoid
breaking out-of-tree modules. If needed, add another macro that
increases the number of bits that can be used to check for sublevels >
255, while keeping the old macros for compatibility reasons. Since
sublevels > 255 have never existed before, any such checks must be
newly-added, so they can be required to use the new macros.
I do not run the 4.4/4.9 kernels usually, but I do sometimes test a wide
range of kernels from 3.18 (gasp!) up to the latest when bisecting,
benchmarking, or debugging problems. And I use a number of out-of-tree
modules that rely on the KERNEL_VERSION to make everything work. Some
out-of-tree modules like an updated igb network driver might be needed
to make it possible to test the old kernel on particular hardware.
In the worst case, I can patch LINUX_VERSION_CODE and KERNEL_VERSION
locally to make out-of-tree modules work. Or else just not test kernels
with sublevel > 255.
Tony Battersby
Cybernetics
next prev parent reply other threads:[~2021-02-05 17:51 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-04 5:59 Kernel version numbers after 4.9.255 and 4.4.255 Jari Ruusu
2021-02-04 6:20 ` Greg Kroah-Hartman
2021-02-04 7:26 ` Jiri Slaby
2021-02-04 8:51 ` Greg Kroah-Hartman
2021-02-04 11:00 ` Jiri Slaby
2021-02-04 16:28 ` David Laight
2021-02-04 16:48 ` Greg Kroah-Hartman
2021-02-04 20:19 ` Christoph Biedl
2021-02-05 6:52 ` Greg KH
2021-02-05 17:31 ` Tony Battersby [this message]
2021-02-05 18:11 ` Mauro Carvalho Chehab
2021-02-06 7:20 ` Greg Kroah-Hartman
2021-02-06 9:24 ` Mauro Carvalho Chehab
2021-02-06 9:29 ` Greg Kroah-Hartman
2021-02-06 9:48 ` Mauro Carvalho Chehab
2021-02-06 10:18 ` Hans Verkuil
2021-02-06 11:18 ` Mauro Carvalho Chehab
2021-02-06 7:22 ` Greg Kroah-Hartman
2021-02-05 9:06 ` Pavel Machek
2021-02-05 9:33 ` Greg Kroah-Hartman
2021-02-05 18:44 ` Pavel Machek
2021-02-06 7:23 ` Greg Kroah-Hartman
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