[yocto] Problems building U-Boot for x86_64

Thu Aug 24 06:09:51 PDT 2017

Op Thu, 24 Aug 2017 12:40:57 +0200, schreef Stefano Babic:

> Hi Ferry,
> 
> On 24/08/2017 08:51, Ferry Toth wrote:
>> Op Wed, 23 Aug 2017 21:07:56 -0700, schreef Khem Raj:
>> 
>>> On 8/23/17 3:40 PM, Ferry Toth wrote:
>>>> Op Wed, 23 Aug 2017 14:51:55 -0700, schreef Khem Raj:
>>>>
>>>>> On 8/23/17 2:29 PM, Ferry Toth wrote:
>>>>>> Ferry Toth wrote:
>>>>>>
>>>>>>> Khem Raj wrote:
>>>>>>>
>>>>>>>> On 8/22/17 11:41 PM, Ferry Toth wrote:
>>>>>>>>> I am having trouble building a specific U-Boot version with
>>>>>>>>> Yocto.
>>>>>>>>> Outside of Yocto on 64 bit Ubuntu 17.04 with multilib it builds
>>>>>>>>> fine.
>>>>>>>>>
>>>>>>>>> I am extending meta-intel-edison to build a 64 bit Poke Morty,
>>>>>>>>> with a vanilla 64-bit kernel (4.12). This is working quite well.
>>>>>>>>>
>>>>>>>>> My host is x86_64, the target is core2 with tune=core-64.
>>>>>>>>>
>>>>>>>>> Without 64bit tune I can build U-Boot fine. With 64bit it can
>>>>>>>>> not link, appearently because it needs lbgcc.a
>>>>>>>>
>>>>>>>> what is exact error message ? is it while compiling host bits or
>>>>>>>> target bits ?
>>>>>>>
>>>>>>> The failing line is:
>>>>>>> x86_64-poky-linux-ld.bfd -Bsymbolic -Bsymbolic-functions -m
>>>>>>> elf_i386 --emit- relocs --wrap=__divdi3 --wrap=__udivdi3
>>>>>>> --wrap=__moddi3 --wrap=__umoddi3 -- gc-sections -pie -Bstatic
>>>>>>> --no-dynamic-linker -Ttext 0x01101000 -o u-boot -T u-boot.lds
>>>>>>> arch/x86/cpu/start.o --start-group arch/x86/cpu/built-in.o
>>>>>>> arch/x86/lib/built-in.o board/intel/edison/built-in.o
>>>>>>> cmd/built-in.o common/built-in.o disk/built-in.o
>>>>>>> drivers/built-in.o drivers/dma/built-in.o drivers/gpio/built-in.o
>>>>>>> drivers/i2c/built-in.o drivers/mmc/built-in.o
>>>>>>> drivers/mtd/built-in.o drivers/mtd/onenand/built-in.o
>>>>>>> drivers/mtd/spi/built- in.o drivers/net/built-in.o
>>>>>>> drivers/net/phy/built-in.o drivers/pci/built-
>>>>>>> in.o drivers/power/built-in.o drivers/power/battery/built-in.o
>>>>>>> drivers/power/domain/built-in.o
>>>>>>> drivers/power/fuel_gauge/built-in.o drivers/power/mfd/built-in.o
>>>>>>> drivers/power/pmic/built-in.o drivers/power/regulator/built-in.o
>>>>>>> drivers/serial/built-in.o drivers/spi/built-in.o
>>>>>>> drivers/usb/common/built-in.o drivers/usb/dwc3/built- in.o
>>>>>>> drivers/usb/emul/built-in.o drivers/usb/eth/built-in.o
>>>>>>> drivers/usb/gadget/built-in.o drivers/usb/gadget/udc/built-in.o
>>>>>>> drivers/usb/host/built-in.o drivers/usb/musb-new/built-in.o
>>>>>>> drivers/usb/musb/built-in.o drivers/usb/phy/built-in.o
>>>>>>> drivers/usb/ulpi/built-in.o dts/built-in.o fs/built-in.o
>>>>>>> lib/built-in.o net/built-in.o test/built-in.o test/dm/built-in.o
>>>>>>> --end-group arch/x86/lib/lib.a -Map u-boot.map ERROR: oe_runmake
>>>>>>> failed arch/x86/lib/built-in.o: In function `__wrap___udivdi3':
>>>>>>> /home/ferry/tmp/edison-intel/my/edison-
>>>>>>> morty/out/linux64/build/tmp/work/edison-poky-linux/u-boot/edison-
>>>> v2017.03-
>>>>>>> r0/git/arch/x86/lib/gcc.c:25: undefined reference to
>>>>>>> `__normal___udivdi3'
>>>>>>
>>>>>> I as believe the missing lib is libgcc.a I just my sysroot and
>>>>>> found it here:
>>>>>
>>>>> the linker cmdline above does not link with libgcc and there might
>>>>> be a good reason for that, many standalone applications dont link
>>>>> with libgcc intentionally. You could look into the code and see if
>>>>> it can be written differently such that gcc does not have to invoke
>>>>> a helper function from gcc runtime. Another option is to link with
>>>>> libgcc explicitly
>>>>
>>>> If change my setup to build for a 32bit target, it build u-boot
>>>> without error.
>>>
>>> compiler may not be generating calls for the missing function.
>> 
>> That would be a bug then? Regardless if I set tune=core-64 or not the
>> resulting U-Boot should be the same.
>> 
>>>> When I build the same git outside yocto on 64bit with multilib
>>>> installed it also builds without error. In that case the make command
>>>> would be: make -j8 edison_defconfig
>>>
>>> same is possible. Can you do readelf -sW gcc.o and see if there is a
>>> undefined reference to __normal___udivdi3
>>>
>> I will do that tonight.
>> 
>>>> My conclusion: I have some bb variable set to the wrong value or I
>>>> need to get multilib installed into /..../sysroots/x86_64-linux/lib.
>>>>
>>>> So how to do that?
>>>>
>>>>>> sysroots/lib32-edison/usr/lib/i686-pokymllib32-linux/6.2.0/
>>>>>> sysroots/lib32-edison-tcbootstrap/usr/lib/i686-pokymllib32-
>> linux/6.2.0/
>>>>>> sysroots/edison/usr/lib64/x86_64-poky-linux/6.2.0/
>>>>>> sysroots/edison-tcbootstrap/usr/lib64/x86_64-poky-linux/6.2.0/
>>>>>>
>>>>>> How compile log shows:
>>>>>> NOTE: make -j8 CROSS_COMPILE=x86_64-poky-linux-
>>>>>> CC=x86_64-poky-linux-gcc --sysroot=/..../sysroots/edison V=1
>>>>>> HOSTCC=gcc -isystem/..../sysroots/x86_64-linux/usr/include -O2
>>>>>> -pipe -L/..../sysroots/x86_64-linux/usr/lib
>>>>>> -L/..../sysroots/x86_64-linux/lib
>>>>>> -Wl,-rpath-link,/..../sysroots/x86_64-linux/usr/lib
>>>>>> -Wl,-rpath-link,/..../sysroots/x86_64-linux/lib
>>>>>> -Wl,-rpath,/..../sysroots/x86_64-linux/usr/lib
>>>>>> -Wl,-rpath,/..../sysroots/x86_64-linux/lib -Wl,-O1 -C
>>>>>> /..../out/linux64/build/tmp/work/edison-poky-linux/u-boot/edison-
>>>>>> v2017.03-r0/git
>>>>>> O=/..../out/linux64/build/tmp/work/edison-poky-linux/u-
>>>>>> boot/edison-v2017.03-r0/build edison_defconfig
>>>>>>
>>>>>> (.... my edits to shorten the uninteresting part of the path)
>>>>>>
>>>>>> I would think: --sysroot points to /edison dir which actually
>>>>>> contains libgcc.a, but -i, _l and -W1 options point to host dirs
>>>>>> that don't have the lib.
>>>>>>
>>>>>>
>>>>>>>>> I attempted to add multilib, but although that immediately
>>>>>>>>> exposed bugs in other recipes but actually adds libgcc.a, it
>>>>>>>>> does that for the target sysroot only.
>>>>>>>>>
>>>>>>>>> And for some reason, U-Boot is built with the native gcc
>>>>>>>>> (x86_64-linux),
>>>>>>>>> and multilib does not add libgcc.a to that sysroot.
>>>>>>>>>
>>>>>>>>> So, how do I add multilib to -native sysroot, preferably only to
>>>>>>>>> -native and not to the target, as the target has not further use
>>>>>>>>> for it?
>>>>>>>>>
>>>>>>>>> Strangest thing is in u-boot.inc there is:
>>>>>>>>> EXTRA_OEMAKE = 'CROSS_COMPILE=${TARGET_PREFIX}
>>>>>>>>> CC="${TARGET_PREFIX}gcc ${TOOLCHAIN_OPTIONS}" V=1'
>>>>>>>>> EXTRA_OEMAKE += 'HOSTCC="${BUILD_CC} ${BUILD_CFLAGS}
>>>>>>>>> ${BUILD_LDFLAGS}"'
>>>>>>>>>
>>>>>>>>> But when I check my log file:
>>>>>>>>> NOTE: make -j8 CROSS_COMPILE=x86_64-poky-linux-
>>>>>>>>> CC=x86_64-poky-linux- gcc  ......
>>>>>>>>>
>>>>>>>>> So TARGET_PREFIX resolves to x86_64-poky-linux, but I think my
>>>>>>>>> target is core2_64 (or something like that). Is that normal for
>>>>>>>>> U-Boot?
>>>>>>>>
>>>>>>>> thats ok.
>>>>>>>>
>>>>>>>>
>>>>>>>>> I am a little lost, so any help would be greatly appreciated!
>>>>>>>>>
>>>>>>>>> Ferry
> 
> This is a known problem in U-Boot for x86 and it is not yet *cleaned*
> solved. U-Boot for x86 is a 32 bit - there are just disadvantages to go
> to 64 bit version because it is overkilling for a bootloader . The issue

Alright then. But I didn't intend to build a 64 bit U-Boot. I intended to 
build a 64 bit image, which consists in the end of 3 binary image, U-
Boot, Linux and rootfs. The bitness of U-Boot should not depend on either 
host or target bitness, it should only depend on the architectures 
requirements.

> is, as you have found, the libgcc.a library, because the library
> supplied with the host distro is used. This is solved in an elegant way
> with other architectures (PowerPC, ARM) because the required (just a
> few) functions taken from libgcc.a are reimplemented in U-Boot (see
> CONFIG_USE_PRIVATE_LIBGCC, too.) . But this was not done for X86,
> because host and target shared (until 64 bit came) the same architecture
> and the host library is taken. However, this breaks in Yocto because the
> generated library (and then, 64 bit) is taken.

Still don't get this. When I build outside of Yocto on a 64 bit host, it 
just builds. U-Boot's make file already selects the correct target 
bitness and finds the correct libraries.
To me that sounds like that building inside Yocto should just work too, 
if I just get the configuration right.

And correct me if I'm wrong, to do that that I need to force Yocto to 
build 32 bit target, in case of U-Boot (lib32-u-boot?). Or override 
tune=core-64 for U-Boot only?

Still, when I build on my host outside of Yocto I don't need to do any of 
this. And the linker probably uses 32 bit copy of libgcc.a installed with 
multilib on my host.

Hence my question: Yocto has multilib, which in this case installs 32 bit 
libs into the targets sysroot. And I suspect I need to install 32 bit 
libs into the -native sysroot. How to do that? All the documentation I 
found are related to installing libs into the target image.

> The right and cleanest solution should be to fix in U-Boot just as it
> was done with other architectures.

I think I saw something upstreamed related to this, I'd prefer to wait 
till that lands. But I will try to let Yocto apply a patch, instead of 
adding to my git.

> The workaround I used in a couple of projects is to store in my custom
> meta layer a 32 bit copy of libgcc.a and patch U-Boot to use this
> instead of the library in the distro, that is in :
> 
> 
> diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile index
> e17f0bb..62764ec 100644 --- a/arch/x86/lib/Makefile +++
> b/arch/x86/lib/Makefile @@ -40,7 +40,9 @@ obj-$(CONFIG_HAVE_FSP) += fsp/
> 
>  extra-$(CONFIG_USE_PRIVATE_LIBGCC) += lib.a
> 
> -NORMAL_LIBGCC = $(shell $(CC) $(PLATFORM_CPPFLAGS)
> -print-libgcc-file-name) +#NORMAL_LIBGCC = $(shell $(CC)
> $(PLATFORM_CPPFLAGS)
> -print-libgcc-file-name)
> +NORMAL_LIBGCC = $(PWD)/arch/$(ARCH)/lib/libgcc.a
>  OBJCOPYFLAGS := --prefix-symbols=__normal_ $(obj)/lib.a:
>  $(NORMAL_LIBGCC) FORCE
> +       echo "Library GCC" ${NORMAL_LIBGCC}
>         $(call if_changed,objcopy)
> --
> 
> I hope this helps.
> 
> Best regards,
> Stefano Babic
> 
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