Re: [PATCH 0/9] x86-64 put current in r10

Andi Kleen
2005-11-30T12:45:19Z

> Your patch breaks all out-of-tree amd64 assembler code used in kernel. r10
> register is one of those registers that does not need to be preserved across
> function calls, and reserving that register for other purpose means that all
> assembler code using r10 in kernel must be rewritten. This is deeply
> unfunny.

Well, the changes should be minor.

>
> Please don't apply Ben's patch. It is already bad enough having to deal with
> two incompatible calling conventions on 32 bit x86.

43KB .text savings are hard to argue against. There is no guarantee
for a stable kernel ABI. If you maintain out of tree code you
will need to live with the occasional changes.

-Andi