Gentoo Archives: gentoo-user

From:	James Cloos <cloos@×××××××.com>
To:	Nilesh Govindrajan <me@××××××××.com>
Cc:	Gentoo User Mailing List <gentoo-user@l.g.o>
Subject:	Re: [gentoo-user] -march=? for this cpu
Date:	Tue, 09 Apr 2013 21:05:33
Message-Id:	`m3vc7v4drq.fsf@carbon.jhcloos.org`
In Reply to:	[gentoo-user] -march=? for this cpu by Nilesh Govindrajan

1	>>>>> "NG" == Nilesh Govindrajan <me@××××××××.com> writes:
2
3	NG> I have two Gentoo VMs at Hetzner and the CPU supports 64 bit (grep lm
4	NG> /proc/cpuinfo = true).
5
6	NG> model name : QEMU Virtual CPU version 1.0
7
8	march=native does not work on a QEMU virtual.
9
10	In the past I had success doing this on such VMs:
11
12	gcc -dM -E - </dev/null \|sort >/tmp/arch-none
13	gcc -march=native -dM -E - </dev/null \|sort >/tmp/arch-native
14	diff -U0 /tmp/arch-none /tmp/arch-native
15
16	gcc-4.4 and gcc-4.5 provide useful results from the formula;
17	4.6 and newer do not.
18
19	-JimC
20	--
21	James Cloos <cloos@×××××××.com> OpenPGP: 1024D/ED7DAEA6