Re: linux-next: build failure after merge of the tip tree

[Sedat Dilek]

On Tue, Mar 1, 2016 at 8:39 AM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> On February 29, 2016 11:28:22 PM PST, Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote:
>>On Tue, Mar 1, 2016 at 8:07 AM, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
>>>
>>> * Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote:
>>>
>>>> Hi all,
>>>>
>>>> After merging the tip tree, today's linux-next build (x86_64
>>allmodconfig)
>>>> failed like this:
>>>>
>>>>   DESCEND  objtool
>>>>   CC
>>/home/sfr/next/x86_64_allmodconfig/tools/objtool/builtin-check.o
>>>>   CC
>>/home/sfr/next/x86_64_allmodconfig/tools/objtool/special.o
>>>>   CC       /home/sfr/next/x86_64_allmodconfig/tools/objtool/elf.o
>>>>   CC
>>/home/sfr/next/x86_64_allmodconfig/tools/objtool/objtool.o
>>>>   MKDIR
>>/home/sfr/next/x86_64_allmodconfig/tools/objtool/arch/x86/insn/
>>>>   CC
>>/home/sfr/next/x86_64_allmodconfig/tools/objtool/libstring.o
>>>> elf.c:22:23: fatal error: sys/types.h: No such file or directory
>>>> compilation terminated.
>>>>   CC
>>/home/sfr/next/x86_64_allmodconfig/tools/objtool/exec-cmd.o
>>>>   CC       /home/sfr/next/x86_64_allmodconfig/tools/objtool/help.o
>>>> builtin-check.c:28:20: fatal error: string.h: No such file or
>>directory
>>>> compilation terminated.
>>>> objtool.c:28:19: fatal error: stdio.h: No such file or directory
>>>> compilation terminated.
>>>>
>>>> and further errors ...
>>>>
>>>> This build is done with a PowerPC hosted cross compiler with no
>>glibc.
>>>
>>> Ugh, what a rare and weird way to build an x86 kernel, and you made
>>linux-next
>>> dependent on it?
>>>
>>>> I assume that some things here need to be built with HOSTCC?
>>>
>>> I suspect that's the culprit. Do you now mandate people to have
>>PowerPC systems as
>>> a requirement to merge to linux-next? How are people supposed to be
>>able to test
>>> that rare type of build method which does not matter to 99.99% of our
>>kernel
>>> testers and users?
>>>
>>
> >From my experience in using different $COMPILER you should always pass
>>CC and HOSTCC in your make-line when building a Linux-kernel or
>>playing with the Kconfig-system.
>>
>>When building my llvm-toolchain with make/autoconf I had also to pass
>>CC and CXX to my configure-line otherwise you got misconfiguration.
>>
>>[ EXAMPLE: Linux Kconfig-system ]
>>
>>$ MAKE="make V=1" ; COMPILER="mycompiler" ; MAKE_OPTS="CC=$COMPILER
>>HOSTCC=$COMPILER"
>>
>>$ yes "" | $MAKE $MAKE_OPTS oldconfig && $MAKE $MAKE_OPTS
>>silentoldconfig < /dev/null
>>
>>- Sedat -
>
> That is not the issue here.  The problem is clearly that objtool is a host program and not compiled with host cc.  So it is a good thing to test even though it is weird, because it affects real use cases.
>
> As x86 is far and beyond the most widely used host architecture, cross-compiling x86 is more likely to involve compiler differences than actually using another host, or possibly compiling 32 bits on a system without the 32-bit libc installed, but it should still work.
>

Thanks for the clarification.

I talked about my experiences in software building in general.

When this is a "tools/objtool problem" then someone should address
this to "tools/objtool maintainers/folks" or whoever else is
responsible.

- Sedat -