Re: Set arch_minimum_kernel for powerpc*le

["Joseph S. Myers" <joseph at codesourcery dot com>]

On Thu, 16 Jan 2014, Alan Modra wrote:

> You are correct that the first kernel.org release with working support
> was 3.13.  However, there are unofficial kernels dating back to 3.10,
> and sometimes distros backport support for particular features to an
> older kernel.  That's why I chose 3.10.  --enable-kernel doesn't allow
> you to specify less than arch_minimum_kernel.

Distros can of course have a local change to arch_minimum_kernel (and that 
won't break any sort of compatibility).  The practice followed for ARM 
EABI, AArch64, x32 etc. is to use the minimum kernel version with the 
relevant support rather than the first version for which support was 
posted.  (For ARM EABI of course the version is now the minimum glibc 
supports at all - but when added to glibc, 2.6.16 reflected when the 
support went in the kernel, whereas the patches were first posted for 
2.6.14 and some people used 2.6.14 kernels with the patches.)

The reasoning is that when doing global cleanups, the given version is the 
earliest one you ever need to look at to see what kernel support was 
present when - and you never need when doing such cleanups to look at any 
unofficial patches, only actual kernel.org release versions (or git for 
very new features).  If the version number used is 10.0.0 (kernel support 
not yet upstream at all, as in the MIPS NaN2008 case) then it's up to the 
relevant architecture maintainers to help in such cases as needed.

-- 
Joseph S. Myers
joseph@codesourcery.com