Re: [PATCH] Fix CFLAGS overwrite by Makefile

Hi,

On Wed, May 25, 2011 at 12:28 PM, John Baldwin <jhb_at_freebsd.org> wrote:
> On Wednesday, May 25, 2011 11:34:29 am Arnaud Lacombe wrote:
>> 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.
>
> Huh?  GCC does not generate i686 instructions by default on FreeBSD/i386.  It
> generates i486 instructions but that is all.
something is odd somewhere.

> Are you sure you aren't running
> the 64-bit gcc (which will generate i686 instructions by default)?
>
yes.

# which gcc
/usr/bin/gcc

# file /usr/bin/gcc
/usr/bin/gcc: ELF 32-bit LSB executable, Intel 80386, version 1
(FreeBSD), for FreeBSD 7.1, statically linked, FreeBSD-style, stripped

# gcc -v
Using built-in specs.
Target: i386-undermydesk-freebsd
Configured with: FreeBSD/i386 system compiler
Thread model: posix
gcc version 4.2.1 20070719  [FreeBSD]

# uname -a
FreeBSD build 7.2-RELEASE FreeBSD 7.2-RELEASE #0: Fri May  1 07:18:07
UTC 2009     root_at_driscoll.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC
 amd64

The  fact that /usr/bin/gcc is statically linked made me think we may
have built internally, but it is also statically linked on a 8.2
machine from release packages.

 - Arnaud