[PATCH u-boot 16/39] build: use thin archives instead of incremental linking

[Bin Meng]

Hi Marek,

On Mon, Mar 8, 2021 at 9:24 PM Marek Behún <marek.behun at nic.cz> wrote:
>
> On Mon, 8 Mar 2021 19:32:10 +0800
> Bin Meng <bmeng.cn at gmail.com> wrote:
>
> > On Mon, Mar 8, 2021 at 7:18 PM Marek Behun <marek.behun at nic.cz> wrote:
> > >
> > > On Mon, 8 Mar 2021 18:44:58 +0800
> > > Bin Meng <bmeng.cn at gmail.com> wrote:
> > >
> > > > Could you investigate why?
> > >
> > > I could, but I don't understand why exactly I should
> > > - Linux is also using --whole-archive
> > > - it is working
> > > - I have other things I would like to work on
> > >
> > > Maybe you could look into this? :)
> >
> > Yes, I can look into this. I wonder if you already knew this which
> > could save some time as this is a normal review process, asking for
> > clarifications if something isn't clear.
>
> Bin, CI is failing without the --whole-archive option.
>
> What is interesting is that the binaries build successfully, but
> testing them fails :)
>
> You can try this (with and without the --whole-archive options) (note
> that this is without LTO)
>   make qemu_arm_defconfig
>   CROSS_COMPILE=arm-compiler- make -j8
>   qemu-system-arm -M virt -nographic \
>     -netdev user,id=net0,tftp=$(pwd) \
>     -device e1000,netdev=net0 -device virtio-rng-pci \
>     -bios u-boot.bin -serial mon:stdio
>
> With --whole-archive option this boots successfully into U-Boot,
> without --whole-archive it just hangs.

Thanks for reporting. My initnial build testing on qemu_arm_defconfig
with this series succeeded but there are some warnings:

/opt/armv7-linux/bin/arm-linux-ld.bfd:
lib/efi_selftest/efi_selftest_miniapp_exception.o: plugin needed to
handle lto object
/opt/armv7-linux/bin/arm-linux-ld.bfd:
examples/standalone/hello_world.o: plugin needed to handle lto object
/opt/armv7-linux/bin/arm-linux-ld.bfd: examples/standalone/libstubs.o:
plugin needed to handle lto object
/opt/armv7-linux/bin/arm-linux-ld.bfd: warning: cannot find entry
symbol hello_world; defaulting to 000000000c100000

It looks we should update the make rules to remove "-flto" for these targets.

Applying the following diff to remove --whole-archive, I got a build error:

diff --git a/Makefile b/Makefile
index 0f538270d7..127630e060 100644
--- a/Makefile
+++ b/Makefile
@@ -1780,7 +1780,7 @@ quiet_cmd_u-boot__ ?= LTO     $@
                $(LTO_FINAL_CFLAGS) $(c_flags)
         \
                $(KBUILD_LDFLAGS:%=-Wl,%) $(LDFLAGS_u-boot:%=-Wl,%) -o
$@       \
                -T u-boot.lds $(u-boot-init)
         \
-               -Wl,--start-group -Wl,--whole-archive
         \
+               -Wl,--start-group
         \
                        $(u-boot-main)
         \
                        $(PLATFORM_LIBS)
         \
                -Wl,--no-whole-archive -Wl,--end-group
         \
@@ -1790,9 +1790,9 @@ else
 quiet_cmd_u-boot__ ?= LD      $@
       cmd_u-boot__ ?= $(LD) $(KBUILD_LDFLAGS) $(LDFLAGS_u-boot) -o $@
         \
                -T u-boot.lds $(u-boot-init)
         \
-               --start-group --whole-archive
         \
+               --start-group
         \
                        $(u-boot-main)
         \
-               --no-whole-archive --end-group
         \
+               --end-group
         \
                $(PLATFORM_LIBS) -Map u-boot.map;
         \
                $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
 endif

  LTO     u-boot
/opt/armv7-linux/bin/../lib/gcc/arm-buildroot-linux-gnueabihf/9.3.0/../../../../arm-buildroot-linux-gnueabihf/bin/ld:
arch/arm/lib/lib.a(lib1funcs.o): in function `Ldiv0':
arch/arm/lib/lib1funcs.S:360: undefined reference to `__div0'

I am using a pre-built armv7 toolchain from https://toolchains.bootlin.com/

Regards,
Bin