[U-Boot] [PATCH] ARM: compiler options cleanup - improve tool chain support

[Magnus Lilja]

Hi Wolfgang,

2009/8/17 Wolfgang Denk <wd at denx.de>:
> For some time there have been repeated reports about build problems
> with some ARM (cross) tool chains.  Especially issues about
> (in)compatibility with the tool chain provided runtime support
> library libgcc.a caused to add and support a private implementation
> of such runtime support code in U-Boot.  A closer look at the code
> indicated that some of these issues are actually home-made.  This
> patch attempts to clean up some of the most obvious problems and make
> building of U-Boot with different tool chains easier:
>
> - Even though all ARM systems basicy used the same compiler options
>  to select a specific ABI from the tool chain, the code for this was
>  distributed over all cpu/*/config.mk files.  We move this one level
>  up into lib_arm/config.mk instead.
>
> - So far, we only checked if "-mapcs-32" was supported by the tool
>  chain; if yes, this was used, if not, "-mabi=apcs-gnu" was
>  selected, no matter if the tool chain actually understood this
>  option.  There was no support for EABI conformant tool chains.
>  This patch implements the following logic:
>
>  1) If the tool chain supports
>        "-mabi=aapcs-linux -mno-thumb-interwork"
>     we use these options (EABI conformant tool chain).
>  2) Otherwise, we check first if
>        "-mapcs-32"
>     is supported, and then check for
>        "-mabi=apcs-gnu"
>     If one test succeeds, we use the first found option.
>  3) In case 2), we also test if "-mno-thumb-interwork", and use
>     this if the test succeeds. [For "-mabi=aapcs-linux" we set
>     "-mno-thumb-interwork" mandatorily.]
>
>  This way we use a similar logic for the compile options as the
>  Linux kenrel does.

"kenrel" => "kernel" :-)

>
> - Some EABI conformant tool chains cause external references to
>  utility functions like raise(); such functions are provided in the
>  new file lib_arm/eabi_compat.c
>
>  Note that lib_arm/config.mk gets parsed several times, so we must
>  make sure to add eabi_compat.o only once to the linker list.
>
> Signed-off-by: Wolfgang Denk <wd at denx.de>
> Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj at jcrosoft.com>
> Cc: Dirk Behme <dirk.behme at googlemail.com>
> Cc: Magnus Lilja <lilja.magnus at gmail.com>
> Cc: Tom Rix <Tom.Rix at windriver.com>
> Cc: Prafulla Wadaskar <prafulla at marvell.com>
> ---
>
> I have run a full "MAKEALL arm" for ELDK releases 3.1 (gcc 3.3.3),
> 3.1.1 (gcc 3.3.3), 4.1 (gcc 4.0.0) and 4.2 (gcc 4.2.2, both as "arm"
> [softfloat] and "armVFP" [VFP hardfloat]), and all of these both with
> USE_PRIVATE_LIBGCC=yes (i. e. using U-Boot internal libgcc
> replacement code) and without (i. e. using the tool chain provided
> standard libgcc instead).
>
> The ELDK fails to build the big-endian IXP boards, but this is a
> restriction of the ELDK, not a new issue introcued by this patch.
> Except of this, all build were succesful.
>
> Note 1: Please note that older tool chains (based on binutils versions
> older than 2.16) will have problems with the SORT_BY_ALIGNMENT()
> and SORT_BY_NAME() functions introduced to the linker scripts with
> commit f62fb99941c6. I'll soon submit a patch to fix this issue. Final
> tests are running right now.
>
> Note 2: Even though this is a bigger change, I consider it a bug fix
> and therefor tend to have it included into the upcoming release. Of
> course this requires sufficient test coverage and feedback. Please
> help!!

I've done compile time testing for the ARM11 boards using a gcc 4.1.2
toolchain that I often use and also Codesourcery's 2009-q1 (gcc 4.3.3)
(both with and without USE_PRIVATE_LIBGCC=yes), everything compiles
fine.

I hope to be able to do some run-time testing of some i.MX31 U-boot
binaries later this week, so far I haven't tried them at all.


Regards, Magnus