[Clfs-support] Target specific options...

[sjs205]

That has sorted it thanks Andrew.

How does one go about helping with CLFS development or even just writing 
some of the missing content?

Cheers,

Steven


On 06/02/2011 12:51, Andrew Bradford wrote:
> On Sat, Feb 5, 2011 at 11:49 PM, Steven Swann<sjs205.linux at gmail.com>  wrote:
>> Hello all,
>>
>> I'm having a little trouble with my current ARM build in that I can't seem
>> to get the CFLAGS and BUILD flags set up correctly.
>>
>> Basically, I'm trying to take the compilation one-step further by ensuring
>> that my final system takes advantages of all the possible features of my ARM
>> core, rather than it being designed for the generic ARM architecture. With
>> this in mind, the problems seem to stem from having the flags set up
>> incorrectly.
>>
>> My process so far and the logic behind it:
>>
>> When building the cross compile tools I leave the CFLAGS variable empty and
>> use the following build flags '-mabi=aapcs-linux -mfloat-abi=softfp'. I have
>> chosen the softfp options since the FPU for my processor isn't 100% ieee
>> compatable.
>>
>>  From here I compile the static compiler, build uClibc with the .config
>> supplied, with the only change being support for EABI rather than the OABI.
>> I then compile the final compiler and all seems fine. I leave the remaining
>> configuration of uClibc as is; my logic here is that I wish to compile the
>> tool suit with generic processor options so that I can pass the architecture
>> specific options when compiling the actual target software.
>>
>> Once I am ready to build the target software I simply add the following
>> CFLAGS: "-mcpu=arm1176jzf-s -mtune=arm1176jzf-s -mfpu=vfp".
>>
>> The problems then starts when it comes to using the tool suite with these
>> CFLAGS. At first busybox failed when issuing the make command with:
>>
>> "  CC      applets/applets.o
>> applets/applets.c:1:0: sorry, unimplemented: -mfloat-abi=hard and VFP
>> make[1]: *** [applets/applets.o] Error 1
>> make: *** [applets_dir] Error 2
>> "
>>
>> So I removed the "-mfloat-abi=softfp" build flag and busybox compiles fine.
>> Is this a bug? Since I haven't selected the use of the hard FLU ABI...
>>
>>
>> I then start to try and configure e2fsprogs and this fails too with:
>> "checking for arm-unknown-linux-uclibc-gcc... arm-unknown-linux-uclibc-gcc
>> -mabi=aapcs-linux -mfloat-abi=softfp -Os
>> checking whether the C compiler works... no
>> "
>>
>> If I then remove both of the build flags from the configure command it
>> configures fine:
>> CC="${CC} ${BUILD} -Os" ../configure --prefix=/usr
>>   --with-root-prefix="" --host=${CLFS_TARGET} --disable-tls
>>   --disable-debugfs --disable-e2initrd-helper --disable-nls
>>
>>
>>
>> I have tried a number of options with the building of the toolsuit, I tried
>> adding the target specific options to the uClibc .config but this seemed to
>> make problems worse since I couldn't get busybox to compile using the tools
>> due to "ld, cannot find -lfloat".
>>
>> With this in mind I am a little stuck. If somebody could please give me some
>> guidance on this is would be greatly appreciated. If I am going about it the
>> wrong way then please let me know.
>>
>> sjs105
>>
>> Hardware
>> Target:
>> Samsung s3c6410,
>> ARM core: arm1176jzf-s
>> FPU: VFPv2
>>
>> .bashrc
>> set +h
>> umask 022
>> ARMCROSS=/mnt/arm-cross
>> LC_ALL=POSIX
>> PATH=${ARMCROSS}/cross-tools/bin:/bin:/usr/bin
>> export ARMCROSS LC_ALL PATH
>> unset CFLAGS
>> unset CXXFLAGS
>> export BUILD="-mabi=aapcs-linux -mfloat-abi=softfp"
>> export CLFS_HOST="i486-cross-linux-gnu"
>> export CLFS_TARGET="arm-unknown-linux-uclibc"
>> export CLFS_ARCH="arm"
>> export CLFS_ENDIAN="little"
>> export CC="arm-unknown-linux-uclibc-gcc"
>> export CXX="arm-unknown-linux-uclibc-g++"
>> export AR="arm-unknown-linux-uclibc-ar"
>> export AS="arm-unknown-linux-uclibc-as"
>> export LD="arm-unknown-linux-uclibc-ld"
>> export RANLIB="arm-unknown-linux-uclibc-ranlib"
>> export READELF="arm-unknown-linux-uclibc-readelf"
>> export STRIP="arm-unknown-linux-uclibc-strip"
>> export CFLAGS="-mcpu=arm1176jzf-s -mtune=arm1176jzf-s -mfpu=vfp "
>> export CXXFLAGS="-mcpu=arm1176jzf-s -mtune=arm1176jzf-s -mfpu=vfp"
>>
> Steven,
>
> I know your pain.  I've been grappling with a similar issue over the past week.
> Currently, the embedded book is broken for those wanting to build an
> EABI (aapcs-linux or aapcs ABI) version of GCC for arm.  I'm working
> on fixing it.
>
> To correctly build a GCC that supports the EABI, you need to set your
> CLFS_TARGET triplet to be "arm-unknown-linux-uclibcgnueabi".  Then,
> when you build GCC (both static and final), pass the
> "--with-abi=aapcs-linux" switch in addition to the other switches
> passed.  If you'd like a soft-float only GCC, add the switch
> "--with-float=soft" as well (but if you want to use vfp, you may want
> to use "--with-float=softfp" which will enable hard floating point
> code that falls back on soft if hard isn't available, see Debian wiki
> [http://wiki.debian.org/ArmHardFloatPort] for some good info on these
> choices).
>
> Then, when configuring uClibc, do a "make menuconfig" before the "make
> oldconfig" and switch it from OABI to EABI (like it sounds like you're
> already doing).
>
> When you build packages, then you can use your CFLAGS and CXXFLAGS and
> they should work as you expect, optimizing for your particular variant
> of arm chip.
>
> I've added some info to trac ticket 620
> [http://trac.cross-lfs.org/ticket/620] and 749
> [http://trac.cross-lfs.org/ticket/749] reflecting these things.
>
> Regards,
> Andrew
> _______________________________________________
> Clfs-support mailing list
> Clfs-support at lists.cross-lfs.org
> http://lists.cross-lfs.org/listinfo.cgi/clfs-support-cross-lfs.org