[yocto] Installation of i686 SDK on a x86_64 machine?

[Wolfgang Denk]

Dear Laurentiu,

In message <50FE4900.7020804 at intel.com> you wrote:
> 
> > in previous releases it ha always been possible to install a SDK
> > configured for a i686 machine on both x86 and x86_64 systems.
> > 
> > Since commit c04f5435 "populate_sdk_base.bbclass: use SDK_ARCH instead
> > of SDKMACHINE" this does not work any more; instead, installation will
> > abort with "Error: Installation machine not supported!"
...

> > Is this intended behaviour (and if so, why?) or rather a bug that
> > should be reported and fixed?
> This is the intended behavior. Please check:
> https://bugzilla.yoctoproject.org/show_bug.cgi?id=3269

Sorry, but this bug is about a different problem - the fix overshoots
the mark.

The following combinations of SDK_ARCH and INST_ARCH are possible and
relevant here:

Id	SDK_ARCH	INST_ARCH	Status
==============================================
1	ix86		ix86		works
2	ix86		x86_64		works
3	x86_64		ix86		cannot work
4	x86_64		x86_64		works

The bug report is about case 3 - attempting to install a 64 bit SDK on
a 32 bit machine.  This indeed cannot work and shuld be prevented byy
the installer.

But the current code also prevents case 2, installing 32 bit images on
a 64 bit machine, which works perfectly fine (assuming you have the
needed 32 bit libraries installed).

For any distribution it is very convenient to provide only one set of
images (configured for ix86), as these images will work both on 32 and
64 bit systems.

I consider it a major drawback if you intentionally prevent such use.

Best regards,

Wolfgang Denk

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