[oe] klibc: armv4 bx strikes again

[Andrea Adami]

On Mon, Aug 25, 2014 at 10:08 AM, Andrea Adami <andrea.adami at gmail.com> wrote:
> I've recently discovered that the static klibc binaries produced for
> armv4 contain Illegal instructions.
>
> Eglibc armv4 binaries are ok.
>
> I verified it happens to kexec-tools-klibc and kexecboot-klibc:
>
> andrea at mizar:/oe/oe-core/build/tmp-eglibc/sysroots/x86_64-linux/usr/bin/arm-oe-linux-gnueabi$
> ./arm-oe-linux-gnueabi-objdump -S ./kexecboot-armv4 | grep bx
>    110dc:       012fff1e        bxeq    lr
>    11154:       e12fff1e        bx      lr
>    11160:       e12fff1e        bx      lr
>    11170:       e12fff1e        bx      lr
>    1119c:       e12fff1e        bx      lr
>    11234:       e12fff1e        bx      lr
>    11240:       e12fff1e        bx      lr
>    11250:       e12fff1e        bx      lr
>    11268:       e12fff1e        bx      lr
>    11298:       e12fff1e        bx      lr
>    112b4:       e12fff1e        bx      lr
>    112f0:       e12fff1e        bx      lr
>    115f4:       e12fff1e        bx      lr
> andrea at mizar:/oe/oe-core/build/tmp-eglibc/sysroots/x86_64-linux/usr/bin/arm-oe-linux-gnueabi$
>
> The binaries end-up compiled with following flags:
>
> arm-oe-linux-gnueabi-klcc -march=armv4 -mthumb-interwork -Wall    -o
> kexecboot util.o cfgparser.o devicescan.o evdevs.o fb.o gui.o menu.o
> xpm.o rgb.o tui.o kexecboot.o fstype/fstype.o machine/zaurus.o
>
> This is rather unexpected because klibc carries one specific patch to fix that:
>
> http://cgit.openembedded.org/meta-openembedded/tree/meta-initramfs/recipes-devtools/klibc/klibc-2.0.4/armv4-fix-v4bx.patch
>
> and in fact looking at the produced klibc.config I see indeed LDFLAGS=
> --fix-v4bx and that goes in  *arm-oe-linux-gnueabi-klcc.
>
> There have been big toolchain changes recently so I suspect something
> got broken in oe-core.
> Then there is a patch touching armv4/thumb but it doesn't look
> suspicious at first:
>
> http://cgit.openembedded.org/openembedded-core/commit/meta/conf/machine/include?id=1250d3e009363d20f15bbfaced622c5912a7fb93
>

I guess that the problem is in the above commit...in klibc.bbclass we set:

export CC_armv4_linux-gnueabi = "${TARGET_PREFIX}klcc -march=armv4
-mthumb-interwork"

because we need interworking but no thumb code.

I'll try to further debug that.

Cheers

Andrea



> As for klibc sources, I see only minor changes in the last versions so
> I would say version is irrelevant.
>
> Any hint?
>
> Thanks in advance
>
> Andrea