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

[Tom <Tom.Rix@windriver.com>]

Wolfgang Denk wrote:
> 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.
>
> - 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@denx.de>
> Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
> Cc: Dirk Behme <dirk.behme@googlemail.com>
> Cc: Magnus Lilja <lilja.magnus@gmail.com>
> Cc: Tom Rix <Tom.Rix@windriver.com>
> Cc: Prafulla Wadaskar <prafulla@marvell.com>
>
>   
MAKEALL arm with CodeSourcery's
arm-2008q3-72-arm-none-linux-gnueabi-i686-pc-linux-gnu
arm-2009q1-203-arm-none-linux-gnueabi-i686-pc-linux-gnu

and this patch differ from

USE_PRIVATE_LIBGCC=yes ./MAKEALL arm

only in these targets

actux1 actux2 actux3 actux4 ixdp425 ixdpg425 pdnb3 scpu trab

As already mentioned already by

http://lists.denx.de/pipermail/u-boot/2009-August/058838.html

Tested-by : Tom Rix <Tom.Rix@windriver.com>