[Rpm-maint] RFC: yum+rpm ppc64p7 patches

[Panu Matilainen]

On 03/23/2012 08:22 PM, Phil Knirsch wrote:
> Hi folks.
>
> Here the promised patches to add support for adding a power7 optimized
> arch to ppc64 for rpm and yum.
>
> It's pretty similar to the ARM neon support code from dgilmore, only
> that i needed to add the detection properly in rpm as well.
>
> I've tested them to some degree with a local repository containing
> packages build with --target ppc64p7 and then installing, removing and
> updating the respective package. Selection worked as expected, preferred
> ppc64p7 obviously on a Power7 box.
>
> The detection code is a bit rough, both in yum and rpm, but i didn't
> want to manually parse the C struct from /proc/self/auxv.
>
> Let me know what you think of them. The toolchain guys i spoke with at
> least were already pretty curious about it as they'd like to use it at
> some point as well.

Looks ok to me... except for the AUXV pitfall wrt libraries: if anything 
changes the environment in the window between process start and rpm 
initialization, the AUXV can no longer be reached by looking past 
environ. It wouldn't be much of an issue for rpm itself, but for other 
library users such as python bindings where the rpm module might be 
lazily loaded long long after the process started... so in order to 
reliably get to the AUXV, you end up having to read and parse 
/proc/self/auxv anyway :-/

There's an experimental patch loosely related to AUXV processing here: 
http://lists.rpm.org/pipermail/rpm-maint/attachments/20111103/86e2f734/attachment.ksh. 
That only deals with AT_HWCAP bits though, not AT_PLATFORM which you're 
using so it wont work as-is.

	- Panu -