Bug 175264

Summary:	Default -mcpu breaks compile for Generic system type
Product:	Gentoo Linux	Reporter:	Bryan Østergaard (RETIRED) <kloeri>
Component:	New packages	Assignee:	Daniel Drake (RETIRED) <dsd>
Status:	RESOLVED FIXED
Severity:	normal	CC:	alpha, grknight2k, kernel
Priority:	High
Version:	unspecified
Hardware:	Alpha
OS:	Linux
Whiteboard:
Package list:		Runtime testing required:	---
Attachments:	Suggested patch changing mcpu for generic system type Alpha linux-headers diff to fix asm Alpha kernel sources asm patch

Description Bryan Østergaard (RETIRED) gentoo-dev

2007-04-19 19:55:34 UTC

gcc-4.1 emits .arch ev5 directives when using -mcpu less than ev56 which in turn breaks compiling of generic system type alpha kernels.

See http://lists.debian.org/debian-alpha/2006/11/msg00014.html and http://gcc.gnu.org/ml/gcc/2005-07/msg00371.html threads for lots of details on this problem.

I suggest simply changing mcpu=ev5 to mcpu=ev56 in arch/alpha/Makefile for generic system type to solve this.

Comment 1 Bryan Østergaard (RETIRED) gentoo-dev

2007-04-19 19:56:44 UTC

Created attachment 116756 [details, diff]
Suggested patch changing mcpu for generic system type

Comment 2 Brian Evans 2007-04-20 12:42:46 UTC

Hi, I've been working with kloeri on this as I'm soon to be an AT for alpha.

I read through the posts mentioned in kloeri's comments.

It seems that gcc4+ ignores the compile as (-Wa,m(arch)) when -mcpu=(arch) is used.  Many times this would not be an issue due to greater than or equal arches.

Alpha Kernel is done differently and compiles for a lesser arch than the assembler is looking for.  As such, propose 2 diffs to fix this issue.

One for linux-headers and another for sources.

Comment 3 Brian Evans 2007-04-20 12:45:32 UTC

Created attachment 116790 [details, diff]
Alpha linux-headers diff to fix asm

Comment 4 Brian Evans 2007-04-20 12:46:16 UTC

Created attachment 116791 [details, diff]
Alpha kernel sources asm patch

Comment 5 Bryan Østergaard (RETIRED) gentoo-dev

2007-04-23 13:19:14 UTC

Comment on attachment 116756 [details, diff]
Suggested patch changing mcpu for generic system type

First patch obsoleted by new patches from Brian Evans.

Comment 6 Brian Evans 2007-04-30 13:20:10 UTC

vanilla-sources 2.6.21 fixes this issue

Comment 7 Ricardo Salveti 2007-05-04 02:07:43 UTC

I searched at the Linus' tree and found the commit that probably fix this problem:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff_plain;h=88ed39b064575b4f42ecb737ec2daa66717de173;hp=7fc1a1abc1eca1278d6d37ec54b72005d15b5c1e

I download it and the patch was successfully applied on 2.6.20.

Comment 8 Daniel Drake (RETIRED) gentoo-dev

2007-06-12 13:24:19 UTC

alpha marked 2.6.21 stable so I assume we can close this now