Re: [gentoo-user] Will a 64-bit-no-multilib machine cross-compile 32-bit code?

["Walter Dnes" <waltdnes@waltdnes.org>]

On Mon, Mar 23, 2015 at 06:18:46PM -0400, Mike Gilbert wrote

> You will probably need to add -m32 to CFLAGS to avoid building 64-bit
> objects on the 64-bit machine.

  How could i686-pc-linux-gnu-gcc build 64-bit stuff in the first place?
I followed the instructions, and ran the following on the host 64-bit
machine...

[d531][root][~] crossdev -t -S i686-pc-linux-gnu

[d531][root][~] i686-pc-linux-gnu-gcc --version
i686-pc-linux-gnu-gcc (Gentoo 4.9.2 p1.2, pie-0.6.2) 4.9.2
Copyright (C) 2014 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[d531][root][~] echo 'int main(){return 0;}' > ctest.c
[d531][root][~] i686-pc-linux-gnu-gcc -Wall ctest.c -o ctest
[d531][root][~] file ctest
ctest: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV),
dynamically linked, interpreter /lib/ld-linux.so.2, for GNU/Linux
2.6.32, not stripped

  Here's how far I've gotten with the setup.  Let me know if I'm missing
anything...

=========================================================================

On the host; 64-bit Gentoo on Core2; IP address 192.168.123.251

# emerge crossdev

# crossdev -t -S i686-pc-linux-gnu

# emerge distcc

edit /etc/conf.d/distccd to indicate allowed client(s).  Change the
DISTCCD_OPTS line to...

DISTCCD_OPTS="--port 3632 --log-level notice --log-file /var/log/distccd.log -N 15 --allow 192.168.123.253

get distccd service running now and every boot up (OpenRC)...

# rc-update add distccd default

# rc-service distccd start

  I believe it's OK to leave "-march=native" in the host's make.conf

=========================================================================

  On the client; underpowered ancient 32-bit Atom netbook; 192.168.123.253

# emerge distcc

specify host(s)

# /usr/bin/distcc-config --set-hosts "192.168.123.251"

This modifies /etc/distcc/hosts

In make.conf make the following changes

MAKEOPTS="-j1 -l2"

add "distcc distcc-pump" to FEATURES variable

  Replace "-march=native" in CFLAGS with output of...
# gcc -v -E -x c -march=native -mtune=native - < /dev/null 2>&1 | grep cc1 | perl -pe 's/ -mno-\S+//g; s/^.* - //g;'

  Note that the distcc wiki page gives different instructions here than
the crossdev wiki page.  The command goes out of its way to remove the
"-mno-<whatever>" compiler flags.  This results in (one long line)...

CFLAGS="-O2 -march=atom -msahf -mmovbe -mfxsr --param l1-cache-size=24
--param l1-cache-line-size=64 --param l2-cache-size=512 -mtune=atom
-fstack-protector -mfpmath=sse -fomit-frame-pointer -pipe
-fno-unwind-tables -fno-asynchronous-unwind-tables"

Note that I include "-mfpmath=sse -fomit-frame-pointer -pipe
-fno-unwind-tables -fno-asynchronous-unwind-tables" myself.

=========================================================================

  Now for the questions...
1) https://wiki.gentoo.org/wiki/Distcc#Using_distcc_with_automake
mentions adding...

export PATH="/usr/lib/ccache/bin:/usr/lib/distcc/bin:${PATH}"

...to /etc/env.d/  Is this necessary for Portage/emerge/etc, or is
"automake" something separate?  (You can tell I'm not a programmer, let
alone a developer.)

2) The docs mention running emerge on the client with the command...

# pump emerge -u world

Is that all there is, or am I missing something?  Does it
"automagically" install properly?  Can I assume that...

a) The "pump" command does the lookup in /etc/distcc/hosts for the
appropriate server

b) The line...

CHOST="i686-pc-linux-gnu"

...in the client's make.conf is sufficient to tell emerge to use
"/usr/bin/i686-pc-linux-gnu-gcc" on the host and not "/usr/bin/gcc"?

3) Is this supposed to happen on the host...

=====================================================
[d531][waltdnes][~] gcc-config -l
 [1] i686-pc-linux-gnu-4.9.2 *

 [2] x86_64-pc-linux-gnu-4.8.3 *
=====================================================

Note that the asterisk after "x86_64-pc-linux-gnu-4.8.3" is green.

4) Is the command...

# DISTCC_DIR="" distccmon-text 5
  Or:
# DISTCC_DIR="" distccmon-gnome

...supposed to be run from a seprate terminal?

-- 
Walter Dnes <waltdnes@waltdnes.org>
I don't run "desktop environments"; I run useful applications