[scarthgap] recipe's sysroot misconfiguration in multilib

[Joao Marcos Costa <joaomarcos.costa@bootlin.com>]

Hello,

(Just in case, I'm re-sending this email as the first one bounced back)

I have been trying to set up a multilib environment to generate 
libraries built with Control Flow Integrity support. The gcc toolchain 
is already patched to support this custom multilib ABI, and it is indeed 
capable of generating binaries with the CFI flags.

I am, however, facing this strange issue where a header is not found in 
the multilib recipe-sysroot (i.e., libcfi-recipe-sysroot) of a given 
package (e.g., zstd), and do_compile task fails:

libcfi-zstd/1.5.5/libcfi-recipe-sysroot/usr/include/c++/13.2.0/cstdint:38:10: 
fatal error: bits/c++config.h: No such file or directory
|    38 | #include <bits/c++config.h>
|       |          ^~~~~~~~~~~~~~~~~~
| compilation terminated.
| make: *** [Makefile:248: Options.o] Error 1

The strange part is the header is there:
libcfi-recipe-sysroot/usr/include/c++/13.2.0/riscv64-freedomusdkmllibcfi-linux/bits/c++config.h

Another strange aspect in this very same context is: the 
recipe-sysroot-native seems misconfigured and incomplete. For reference, 
let me use libcfi-zstd/zstd again:

zstd/1.5.5$ ls recipe-sysroot-native/sysroot-providers/ -l | wc -l
66
zstd/1.5.5$ du -sh recipe-sysroot-native/
457M    recipe-sysroot-native/

libcfi-zstd/1.5.5$ ls recipe-sysroot-native/sysroot-providers/ -l | wc -l
27
libcfi-zstd/1.5.5$ du -sh recipe-sysroot-native/
194M    recipe-sysroot-native/

Unless I'm missing something, shouldn't I have roughly the same values here?

Besides my TUNE_*, DEFAULTTUNE, BASE_LIB values set up, I also added
'GCCMULTILIB = "--enable-multilib"' to gcc-cross.inc, to enable multilib 
for the cross toolchain. Could I be missing something, maybe with
recipes-devtools/gcc/gcc-multilib-config.inc?

Any help is very appreciated, and please excuse me for such a text wall.

-- 
Best regards,
João Marcos Costa