On 08/31/2015 01:19 PM, Michael Ellerman wrote:
> On Mon, 2015-08-31 at 15:53 +0800, Boqun Feng wrote:
>> On Mon, Aug 31, 2015 at 04:52:38PM +1000, Benjamin Herrenschmidt wrote:
>>> 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).
>>
>> Got it, thank you ;-)
>>
>> So should we modify Kconfigs of all the platform to reflect this?
>
> Yes. Maybe something like this?
>
> diff --git a/arch/powerpc/platforms/Kconfig.cputype
> b/arch/powerpc/platforms/Kconfig.cputype
> index c140e94..c359f72 100644
> --- a/arch/powerpc/platforms/Kconfig.cputype
> +++ b/arch/powerpc/platforms/Kconfig.cputype
> @@ -415,9 +415,13 @@ config VDSO32
> big endian. That is because the only little endian configuration we
> support is ppc64le which is 64-bit only.
>
> +config CHOOSE_ENDIAN
> + bool
> +
> choice
> prompt "Endianness selection"
> default CPU_BIG_ENDIAN
> + depends on CHOOSE_ENDIAN
> help
> This option selects whether a big endian or little endian kernel
> will
> be built.
> diff --git a/arch/powerpc/platforms/powernv/Kconfig
> b/arch/powerpc/platforms/powernv/Kconfig
> index 604190c..32d5661 100644
> --- a/arch/powerpc/platforms/powernv/Kconfig
> +++ b/arch/powerpc/platforms/powernv/Kconfig
> @@ -18,6 +18,7 @@ config PPC_POWERNV
> select CPU_FREQ_GOV_ONDEMAND
> select CPU_FREQ_GOV_CONSERVATIVE
> select PPC_DOORBELL
> + select CHOOSE_ENDIAN
> default y
>
> config OPAL_PRD
> diff --git a/arch/powerpc/platforms/pseries/Kconfig
> b/arch/powerpc/platforms/pseries/Kconfig
> index 54c87d5..182f485 100644
> --- a/arch/powerpc/platforms/pseries/Kconfig
> +++ b/arch/powerpc/platforms/pseries/Kconfig
> @@ -21,6 +21,7 @@ config PPC_PSERIES
> select HOTPLUG_CPU if SMP
> select ARCH_RANDOM
> select PPC_DOORBELL
> + select CHOOSE_ENDIAN
> default y
>
> config PPC_SPLPAR
or like this, to be consistent with the other *_CPU configs in Kconfig.cputype :
--- a/arch/powerpc/platforms/ps3/Kconfig
+++ b/arch/powerpc/platforms/ps3/Kconfig
@@ -1,6 +1,6 @@
config PPC_PS3
bool "Sony PS3"
- depends on PPC64 && PPC_BOOK3S
+ depends on PPC64 && PPC_BOOK3S && !CPU_LITTLE_ENDIAN
select PPC_CELL
select USB_OHCI_LITTLE_ENDIAN
select USB_OHCI_BIG_ENDIAN_MMIO
>
>
>>> But the specific problem you are having looks like a differnet issue
>>> with the PS3 boot wrapper.
>>>
>>
>> But could the reason of this be that the building process of the PS3
>> boot wrapper assumes the kernel is BE?
>
> It looks more like we're getting confused between 32-bit and 64-bit, from your
> log:
>
> ld: powerpc:common64 architecture of input file
> `arch/powerpc/boot/ps3-head.o' is incompatible with powerpc:common output
>
> Which says it has a .o which is 64-bit but it's trying to produce 32-bit
> output.
>
> That's probably related to the PPC64_BOOT_WRAPPER stuff.
yes. This is because CPU_LITTLE_ENDIAN selects PPC64_BOOT_WRAPPER.
Cheers,
C.
>
> cheers
>
>
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