Re: [PATCH] Fix CFLAGS overwrite by Makefile

From: Arnaud Lacombe <lacombar_at_gmail.com>
Date: Wed, 25 May 2011 11:34:29 -0400
Hi,

On Wed, May 25, 2011 at 9:43 AM, John Baldwin <jhb_at_freebsd.org> wrote:
>> The original trouble I met, is that building for an i586 target in a
>> 32bits jail, on top of an amd64 system[0] (I do not have control over
>> that setup) produces incorrect binaries. The current fix I've got is
>> to define MACHINE_ARCH=i386 and CPUTYPE=i586. This enforces
>> `-march=i586' to be passed to the compiler, for all except the
>> bootloader (because it overwrites CFLAGS). With this, binaries
>> produced works fine (ie. /bin/sh no longer SIGILL when bringing up the
>> system). So I suspect that gcc default to i686 in this setup and
>> corrupt all the binaries, thus the attached patch.
>
> Wait.  You must have something wrong in your jail if you can't do a buildworld
> with CPUTYPE set to none and have it do the right thing.  You need to find
> your root problem.  Forcing CPUCFLAGS for the boot code is a band-aid, it's
> not the right solution to your problem.
>
Unless error of my part, I never mentioned it was using `buildworld',
which it is not. The system uses bare calls to make(1) in the
sys/boot/ directory. As the jail is 32bits, it was expected not to be
an issue, but the jail compiler uses /lib/libstand.a to link the
loader, and it obviously contains i686-only instructions, which
trigger a reset of an i586-only CPU.

The more broad issue with the setup is that gcc within that
environment, without being told -march=i586, produces i686
instructions which are incompatible with the target CPU.

 - Arnaud
Received on Wed May 25 2011 - 13:34:31 UTC

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