Re: Linux 4.9.256

From: Avi Kivity
Date: Mon Feb 08 2021 - 13:26:23 EST


On 05/02/2021 16.26, Greg Kroah-Hartman wrote:
I'm announcing the release of the 4.9.256 kernel.

This, and the 4.4.256 release are a little bit "different" than normal.

This contains only 1 patch, just the version bump from .255 to .256 which ends
up causing the userspace-visable LINUX_VERSION_CODE to behave a bit differently
than normal due to the "overflow".

With this release, KERNEL_VERSION(4, 9, 256) is the same as KERNEL_VERSION(4, 10, 0).


I think this is a bad idea. Many kernel features can only be discovered by checking the kernel version. If a feature was introduced in 4.10, then an application can be tricked into thinking a 4.9 kernel has it.


IMO, better to stop LINUX_VERSION_CODE at 255 and introduce a LINUX_VERSION_CODE_IMPROVED that has more bits for patchlevel.


Nothing in the kernel build itself breaks with this change, but given that this
is a userspace visible change, and some crazy tools (like glibc and gcc) have
logic that checks the kernel version for different reasons, I wanted to do this
release as an "empty" release to ensure that everything still works properly.


Even if glibc and gcc work, other programs may not.


I have two such cases. They don't depend on 4.9, but they're examples of features that are not discoverable by other means.



So, this is a YOU MUST UPGRADE requirement of a release. If you rely on the
4.9.y kernel, please throw this release into your test builds and rebuild the
world and let us know if anything breaks, or if all is well.

Go forth and do full system rebuilds! Yocto and Gentoo are great for this, as
will systems that use buildroot.

I'll try to hold off on doing a "real" 4.9.y release for a 9eek to give
everyone a chance to test this out and get back to me. The pending patches in
the 4.9.y queue are pretty serious, so I am loath to wait longer than that,
consider yourself warned...

The updated 4.9.y git tree can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linux-4.9.y
and can be browsed at the normal kernel.org git web browser:
https://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=summary

thanks,

greg k-h

------------

Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

Greg Kroah-Hartman (1):
Linux 4.9.256