From: "Cédric Le Goater" <clg@fr•ibm.com>
To: Michael Ellerman <mpe@ellerman•id.au>, Boqun Feng <boqun.feng@gmail•com>
Cc: Arnd Bergmann <arnd@arndb•de>, Geoff Levand <geoff@infradead•org>,
Olof Johansson <olof@lixom•net>,
Paul Mackerras <paulus@samba•org>,
Alistair Popple <alistair@popple•id.au>,
Scott Wood <scottwood@freescale•com>,
Anatolij Gustschin <agust@denx•de>,
linuxppc-dev@lists•ozlabs.org
Subject: Re: [Question] Is little endian supported on all the platforms?
Date: Mon, 31 Aug 2015 14:12:54 +0200 [thread overview]
Message-ID: <55E444C6.9070706@fr.ibm.com> (raw)
In-Reply-To: <1441019966.31779.1.camel@ellerman.id.au>
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
>
>
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists•ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev
>
next prev parent reply other threads:[~2015-08-31 12:13 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-31 6:44 [Question] Is little endian supported on all the platforms? Boqun Feng
2015-08-31 6:52 ` Benjamin Herrenschmidt
2015-08-31 7:53 ` Boqun Feng
2015-08-31 8:31 ` Benjamin Herrenschmidt
2015-08-31 11:19 ` Michael Ellerman
2015-08-31 11:56 ` Boqun Feng
2015-09-01 1:39 ` Michael Ellerman
2015-08-31 12:12 ` Cédric Le Goater [this message]
2015-09-01 7:39 ` Boqun Feng
2015-08-31 20:40 ` Benjamin Herrenschmidt
2015-09-01 1:31 ` Michael Ellerman
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