Build failed when enable squashfs support in uboot

[soccercheng]

~/arc/prj/out/host/bin/arc-buildroot-linux-gnu-ld.bfd: fs/built-in.o: in function sqfs_calc_n_blks': ~/arc/prj/out/build/uboot-custom/fs/squashfs/sqfs.c:90: undefined reference to __umoddi3'
~/arc/prj/out/host/bin/arc-buildroot-linux-gnu-ld.bfd: ~/arc/prj/out/build/uboot-custom/fs/squashfs/sqfs.c:90: undefined reference to __umoddi3' ~/arc/prj/out/host/bin/arc-buildroot-linux-gnu-ld.bfd: fs/built-in.o: in function sqfs_read':
~/arc/prj/out/build/uboot-custom/fs/squashfs/sqfs.c:1442: undefined reference to __umoddi3' ~/arc/prj/out/host/bin/arc-buildroot-linux-gnu-ld.bfd: ~/arc/prj/out/build/uboot-custom/fs/squashfs/sqfs.c:1442: undefined reference to __umoddi3'
~/arc/prj/out/host/bin/arc-buildroot-linux-gnu-ld.bfd: /arc/prj/out/build/uboot-custom/fs/squashfs/sqfs.c:1503: undefined reference to __umoddi3' ~/arc/prj/out/host/bin/arc-buildroot-linux-gnu-ld.bfd: fs/built-in.o:~/arc/prj/out/build/uboot-custom/fs/squashfs/sqfs.c:1503: more undefined references to __umoddi3' follow
make[1]: *** [Makefile:1759: u-boot] Error 1
make[1]: Leaving directory '/arc/prj/out/build/uboot-custom'
make: *** [package/pkg-generic.mk:250: /arc/prj/out/build/uboot-custom/.stamp_built] Error 2
make: Leaving directory '/arc/prj/buildroot-2021.02.2'

[abrodkin]

We "imported" a part of libgcc into U-Boot to be toolchain independent, but looks like not all the symbols were used in those builds that we used to play with, thus __umoddi3 is missing. And the simples solution is to not rely on that so-called "private" libs, but use whatever is provided by the toolchain itself. For that just disable CONFIG_USE_PRIVATE_LIBGCC option in U-Boot's configuration (i.e. say make menuconfig and unset it for HSDK).

Let me know if that helps.

[soccercheng]

We "imported" a part of libgcc into U-Boot to be toolchain independent, but looks like not all the symbols were used in those builds that we used to play with, thus __umoddi3 is missing. And the simples solution is to not rely on that so-called "private" libs, but use whatever is provided by the toolchain itself. For that just disable CONFIG_USE_PRIVATE_LIBGCC option in U-Boot's configuration (i.e. say make menuconfig and unset it for HSDK).

Let me know if that helps.

Yes, it worked after disabling CONFIG_USE_PRIVATE_LIBGCC, ---> THANX.

BTW, is CONFIG_USE_PRIVATE_LIBGCC started from "ARC" platform support?

[abrodkin]

BTW, is CONFIG_USE_PRIVATE_LIBGCC started from "ARC" platform support?

Not clear what do you really mean, sorry.
That concept of "private libgcc" existed long before ARC port was introduced I guess. The beauty of "private libgcc" is complete self-contained source tree of U-Boot because no external pre-built libraries (those that otherwise come from the toolchain, typically libgcc.a). Otherwise if you rely on pre-built libgcc.a from the toolchain you have to be sure that library from your toolchain matches your expectations.

See a compiler (for example GCC) may generate object files (.o) for any flavor of the target CPU regardless [compiler] configuration. I.e. even GCC from "big-endian" toolchain may easily produce "little-endian" object files if you pass -mlittle-endian option to it. While libgcc.a of that "big-endian" toolchain will be also "big-endian" and you won't be able to build a "little-endian" U-Boot with "big-endian" toolchain if pre-built libgcc.a is used.

But if libgcc.a (or rather some of its functions) is being built from sources as a part of U-Boot, it's possible to use ARC GNU toolchain of any endianess as well as optimized for any target ARC processor (i.e. GCC configured woth --with-cpu=arcem will build U-Boot for ARC HS perfectly fine).

As an example, with suggested change (disabled "private libgcc") it's no longer possible to use "big-endian" toolchain for building U-Boot for a "little-endian" HSDK, you'll see a lot of such kind of messages during the final linkage stage:

...
arceb-elf32-ld.bfd: arch/arc/lib/start.o: compiled for a big endian system and target is little endian
arceb-elf32-ld.bfd: failed to merge target specific data of file arch/arc/lib/start.o
arceb-elf32-ld.bfd: arch/arc/cpu/arcv2/ivt.o: compiled for a big endian system and target is little endian
arceb-elf32-ld.bfd: failed to merge target specific data of file arch/arc/cpu/arcv2/ivt.o
...

Still this feature ("private libgcc") is more of a convenience option for us U-Boot developers who need to build it for multiple different platforms now and then. For those who work on a particular product with a fixed IP configuration more traditional approach with prebuilt libgcc.a from the toolchain should be good enough.

I hope my explanation makes sense :)