[yocto] question about SDKMACHINE, SDK_ARCH and BUILD_ARCH

[Lu, Lianhao]

Zhang, Jessica wrote on 2011-01-17:
> Richard Purdie wrote:
>> On Thu, 2011-01-13 at 15:36 -0800, Zhang, Jessica wrote:
>>> Hi Richard,
>>> 
>>> As I mentioned in IRC, we've noticed that bitbake behaves 
>>> differently on 64bit and 32bit machines from SDKMACHINE setup 
>>> perspective.  It never enforces SDKMACHINE to be set in local.conf 
>>> for 64bit users but for 32bit user, if you leave SDKMACHINE unset, 
>>> the bitbake sanity test will fail and prompts user to set the SDKMACHINE to i586.
>>> 
>>> It seems internally we really use SDK_ARCH which derived from 
>>> BUILD_ARCH that reflects the poky build machines arch.  And for 
>>> bitbake sanity check if it sees SDK_ARCH is i686, it will prompts 
>>> user to set SDKMACHINE to i586 since there's a known issue for this 
>>> case can't use the default build machine arch of i686.
>>> 
>>> Questions are:
>>> 1. what  is the known issue for using i686?
>> 
>> (e)glibc will fail to build with some issues to do with architecture 
>> optimisations. I don't remember the details but the builds do fail 
>> and the warning is valid. The easy way to test is to disable the 
>> warning and try it!
>> 
>> Once, there were also conflicts between the native bits and the cross 
>> bits both being i686 but I think the problem was solved a long time 
>> ago.
>> 
>> At some point it would be nice to fix this but as far as I know the 
>> problem remains and the sanity warning is still valid.
>> 
> 
> Interestingly, by simply comment off the sanity check for SDK_ARCH == 
> i686, I successfully built meta-toolchain for i686-i586 and 
> poky-image-sdk for x86 and didn't run into (e)glibc build errors.  I 
> check my built toolchain and sysroot, and everything looks right, as 
> host as i686 and target as i586.  I was able to use the cross 
> toolchain to compile a simple c program.  Are these enough test, if so, I'll submitted a patch ...
> 

Jessica,

How about testing against some real project using the meta-toolchain-sdk? e.g. https://oldwiki.pokylinux.org/share/SDK_docs/Test/srcs/ 

Best Regards,
Lianhao