[Question] Is little endian supported on all the platforms?
benh at kernel.crashing.org
Mon Aug 31 16:52:38 AEST 2015
On Mon, 2015-08-31 at 14:44 +0800, Boqun Feng wrote:
> Hi all,
> I hit a strange build error on v4.2, when I try to build a LE kernel
> with a slightly modification of the ppc64_defconfig. What I did is just
> make ppc64_defconfig and make menuconfig to set CPU_LITTLE_ENDIAN=y, and
> then build the kernel.
> I did a little research myself, and found out the error is because of
> trying to build a LE kernel with CONFIG_PPC_PS3=y. So a simple way to
> reproduce is:
First, LE isn't supported on PS/3 :-) It's only supported on POWER8
machines (and *some* P7 machines and only when running as KVM guest).
But the specific problem you are having looks like a differnet issue
with the PS3 boot wrapper.
> 1. make menuconfig
> > set CONFIG_CPU_LITTLE_ENDIAN=y
> > set CONFIG_PPC_PS3=y
> > (I will also attach the .config in the email)
> 2. make
> will see make errors like:
> CALL arch/powerpc/relocs_check.sh
> WARNING: 1 bad relocations
> c000000000c8c778 R_PPC64_ADDR64 __crc_TOC.
> DTC arch/powerpc/boot/ps3.dtb
> WRAP arch/powerpc/boot/dtbImage.ps3
> ld: powerpc:common64 architecture of input file `arch/powerpc/boot/ps3-head.o' is incompatible with powerpc:common output
> ld: powerpc:common64 architecture of input file `arch/powerpc/boot/ps3-hvcall.o' is incompatible with powerpc:common output
> ld: powerpc:common64 architecture of input file `arch/powerpc/boot/ps3.o' is incompatible with powerpc:common output
> arch/powerpc/boot/wrapper.a(crt0.o): In function `p_toc':
> (.text+0x30): undefined reference to `__toc_start'
> arch/powerpc/boot/wrapper.a(crt0.o): In function `p_dyn':
> (.text+0x38): undefined reference to `__dynamic_start'
> arch/powerpc/boot/wrapper.a(crt0.o): In function `p_rela':
> (.text+0x40): undefined reference to `__rela_dyn_start'
> make: *** [arch/powerpc/boot/dtbImage.ps3] Error 1
> rm arch/powerpc/boot/ps3.dtb
> make: *** [zImage] Error 2
> Does this error occur because little endian is not supported on PS3?
> If so, should we do something like:
> config PPC_PS3
> > bool "Sony PS3"
> -> > depends on PPC64 && PPC_BOOK3S
> +> > depends on PPC64 && PPC_BOOK3S && CPU_BIG_ENDIAN
> > select PPC_CELL
> Besides, I don't see any platform stating "depends on CPU_BIG_ENDIAN"
> or "depends on CPU_LITTLE_ENDIAN" in its Kconfig, which means all the
> platforms support both big endian and little endian, at least, based on
> the information provided by Kconfigs.
> Is this true?
> Thanks and Best Regards,
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