Re: [PATCH] scripts: support building with the LSB wrappers

[Michael Hope <michael dot hope at linaro dot org>]

On Tue, Nov 29, 2011 at 7:33 AM, Yann E. MORIN
<yann.morin.1998@anciens.enib.fr> wrote:
> Michael, All,
>
> On Monday 28 November 2011 00:57:27 Michael Hope wrote:
>> # HG changeset patch
>> # User Michael Hope <michael.hope@linaro.org>
>> # Date 1322438185 -46800
>> # Branch lsb
>> # Node ID edadd06cb17fd3a45501afe22ae39a76f4a76fa2
>> # Parent ?49af7802dcd538ec3cb64337030b03ac2c6344d2
>> scripts: support building with the LSB wrappers
>>
>> If set, look for 'lsbcc' instead of 'gcc' and 'lsbc++ instead of g++
>> and use them when building.
>>
>> The Linux Standard Base defines a set of libraries and APIs that are
>> implemented by most distros. ?If you build against these APIs then in
>> theory the program can run on any LSB distro instead of just the
>> host.
>>
>> LSB provide a compiler wrapper for the host C and C++ compilers called
>> 'lsbcc' and 'lsbc++'. ?The wrapper checks the executable name to figure
>> out if you're calling the C or C++ compiler so you have to call these
>> names exactly.
>>
>> Caveats: You need a 4.1 or 4.2 compiler to build. ?Various parts of
>> the toolchain don't compile LSB 3.0+ header files. ?Some parts
>> accidentally use the host include files. ?A patch that works around
>> these is at:
>> ?http://people.linaro.org/~michaelh/keep/00-crosstool-lsb-hacks.patch
>>
>> Nits: I'm abusing the case statement to do an AND but it makes the
>> default value cleaner.
>>
>> Signed-off-by: Michael Hope <michael.hope@linaro.org>
>>
>> diff -r 49af7802dcd5 -r edadd06cb17f config/toolchain.in
>> --- a/config/toolchain.in ? ? Tue Nov 22 10:08:10 2011 +0100
>> +++ b/config/toolchain.in ? ? Mon Nov 28 12:56:25 2011 +1300
>> @@ -247,6 +247,18 @@
>> ? ? ? ?for that by checking the tools without the suffix in case it can
>> ? ? ? ?not find some of the tool.
>>
>> +config BUILD_USE_LSBCC
>> + ? ?bool
>> + ? ?prompt "| ?Build using the Linux Standard Base compilers"
>> + ? ?help
>> + ? ? ?Set to use the LSB C and C++ compiler wrappers lsbcc and
>> + ? ? ?lsbc++ instead of gcc and g++.
>> +
>> + ? ? ?LSB applications are more portable and should run on any LSB
>> + ? ? ?compliant Linux based operating system. ?Note that building
>> + ? ? ?against a LSB 3.0 system may require a pre-4.3 version of GCC
>
> That sounds like a test should be made at runtime to check that the
> available gcc is the correct version.

Not sure on this.  The LSB 3.0 C++ headers don't work with G++ 4.3 or
later due to the __is_pod() builtin.  There's no reason this couldn't
be fixed in LSB 4.0 or later versions.  C only code is unaffected so
if you drop Graphite and GOLD then you're fine.

>> + ? ? ?and local patches to the LSB build tree.
>
> And this sounds like a show-stopper. This would require that the user does
> patch his/her system, and that's definitely not something we want to
> impose on him/her. :-(

Yeah, it's a bit of a mess.  There's things like:
 * /usr/include is still in the include path so non-LSB headers get picked up
 * ctypes.h has trailing commas on the final enum value and g++ 4.1
doesn't like that
 * strings.h has a bzero() which is a builtin or macro somewhere else

All of these are build environment changes and don't affect the LSB
compatibility at least...

>> ?if CANADIAN
>>
>> ?comment "Host system"
>> diff -r 49af7802dcd5 -r edadd06cb17f scripts/crosstool-NG.sh.in
>> --- a/scripts/crosstool-NG.sh.in ? ? ?Tue Nov 22 10:08:10 2011 +0100
>> +++ b/scripts/crosstool-NG.sh.in ? ? ?Mon Nov 28 12:56:25 2011 +1300
>> @@ -390,6 +390,13 @@
>> ? ? ? ? ?fi
>>
>> ? ? ? ? ?for tool in ar as dlltool gcc g++ gcj gnatbind gnatmake ld nm objcopy objdump ranlib strip windres; do
>> + ? ? ? ? ? ?# Re-map GCC and G++ to the corresponding LSB names
>> + ? ? ? ? ? ?case "${CT_BUILD_USE_LSBCC},${m},${tool}" in
>> + ? ? ? ? ? ? ? ?y,BUILD,gcc) ?target="lsbcc";;
>> + ? ? ? ? ? ? ? ?y,BUILD,g++) ?target="lsbc++";;
>> + ? ? ? ? ? ? ? ?*) ? ? ? ? ? ?target="${tool}";;
>> + ? ? ? ? ? ?esac
>
> (OK, I saw your second mail about s/BUILD/HOST/)
> I don't like the 'target' variable name. Why don't you overload the existing
> variable 'tool'?

'tool' is used in the final stub name such as x86_64-foo-linux-gcc.

>> ? ? ? ? ? ? ?# First try with prefix + suffix
>> ? ? ? ? ? ? ?# Then try with prefix only
>> ? ? ? ? ? ? ?# Then try with suffix only, but only for BUILD, and HOST iff REAL_BUILD == REAL_HOST
>> @@ -397,17 +404,17 @@
>> ? ? ? ? ? ? ?# This is needed, because some tools have a prefix and
>> ? ? ? ? ? ? ?# a suffix (eg. gcc), while others may have only one,
>> ? ? ? ? ? ? ?# or even none (eg. binutils)
>> - ? ? ? ? ? ?where=$(CT_Which "${t}${tool}${!s}")
>> - ? ? ? ? ? ?[ -z "${where}" ] && where=$(CT_Which "${t}${tool}")
>> + ? ? ? ? ? ?where=$(CT_Which "${t}${target}${!s}")
>> + ? ? ? ? ? ?[ -z "${where}" ] && where=$(CT_Which "${t}${target}")
>> ? ? ? ? ? ? ?if [ ? ?-z "${where}" ? ? ? ? ? ? ? ? ? ? ? ? \
>> ? ? ? ? ? ? ? ? ? -a \( ? ?"${m}" = "BUILD" ? ? ? ? ? ? ? ?\
>> ? ? ? ? ? ? ? ? ? ? ? ? -o "${CT_REAL_BUILD}" = "${!r}" \) ]; then
>> - ? ? ? ? ? ? ? ?where=$(CT_Which "${tool}${!s}")
>> + ? ? ? ? ? ? ? ?where=$(CT_Which "${target}${!s}")
>> ? ? ? ? ? ? ?fi
>> ? ? ? ? ? ? ?if [ -z "${where}" ? ? ? ? ? ? ? ? ? ? ? ? ? ?\
>> ? ? ? ? ? ? ? ? ? -a \( ? ?"${m}" = "BUILD" ? ? ? ? ? ? ? ?\
>> ? ? ? ? ? ? ? ? ? ? ? ? -o "${CT_REAL_BUILD}" = "${!r}" \) ]; then
>> - ? ? ? ? ? ? ? ?where=$(CT_Which "${tool}")
>> + ? ? ? ? ? ? ? ?where=$(CT_Which "${target}")
>> ? ? ? ? ? ? ?fi
>>
>> ? ? ? ? ? ? ?# Not all tools are available for all platforms, but some are really,
>
> Otherwise, nothing to say. I'll have to look here how it behaves before I
> can comment more.

As always I thought I'd share the patch to see what others think.  I'm
happy to carry it locally.

-- Michael

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