Re: powerpc: 32BIT vs. 64BIT (PPC32 vs. PPC64)

On 07/07/2018 05:13 AM, Nicholas Piggin wrote:

On Fri, 6 Jul 2018 21:58:29 -0700
Randy Dunlap [off-list ref] wrote:

quoted

On 07/06/2018 06:45 PM, Benjamin Herrenschmidt wrote:

quoted

On Thu, 2018-07-05 at 14:30 -0700, Randy Dunlap wrote:  

quoted

Hi,

Is there a good way (or a shortcut) to do something like:

$ make ARCH=powerpc O=PPC32 [other_options] allmodconfig
  to get a PPC32/32BIT allmodconfig

and also be able to do:

$make ARCH=powerpc O=PPC64 [other_options] allmodconfig
  to get a PPC64/64BIT allmodconfig?  

Hrm... O= is for the separate build dir, so there much be something
else.

You mean having ARCH= aliases like ppc/ppc32 and ppc64 ?  

Yes.

quoted

That would be a matter of overriding some .config defaults I suppose, I
don't know how this is done on other archs.

I see the aliasing trick in the Makefile but that's about it.
  

quoted

Note that arch/x86, arch/sh, and arch/sparc have ways to do
some flavor(s) of this (from Documentation/kbuild/kbuild.txt;
sh and sparc based on a recent "fix" patch from me):  

I fail to see what you are actually talking about here ... sorry. Do
you have concrete examples on x86 or sparc ? From what I can tell the
"i386" or "sparc32/sparc64" aliases just change SRCARCH in Makefile and
32 vs 64-bit is just a Kconfig option...  

Yes, your summary is mostly correct.

I'm just looking for a way to do cross-compile builds that are close to
ppc32 allmodconfig and ppc64 allmodconfig.

Would there a problem with adding ARCH=ppc32 / ppc64 matching? This
seems to work...

Thanks,
Nick

Yes, this mostly works and is similar to a patch (my patch) on my test machine.
And they both work for allmodconfig, which is my primary build target.

And they both have one little quirk that is confusing when the build target
is defconfig:

When ARCH=ppc32, the terminal output (stdout) is: (using O=PPC32)

make[1]: Entering directory '/home/rdunlap/lnx/lnx-418-rc3/PPC32'
  GEN     ./Makefile
*** Default configuration is based on 'ppc64_defconfig'   <<<<< NOTE <<<<<
#
# configuration written to .config
#
make[1]: Leaving directory '/home/rdunlap/lnx/lnx-418-rc3/PPC32'


I expect that can be fixed also.  :)

And the written .config file is indeed for 32BIT, not 64BIT.

Thanks, Nick.

-- 
~Randy