linux-kernel - Re: [PATCH 3/3] arm64: configs: unset CPU_BIG

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Date:   Thu, 3 Oct 2019 12:15:32 +0100
From:   John Garry <john.garry@...wei.com>
To:     Anders Roxell <anders.roxell@...aro.org>
CC:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Arnd Bergmann <arnd@...db.de>,
        "Olof Johansson" <olof@...om.net>
Subject: Re: [PATCH 3/3] arm64: configs: unset CPU_BIG_ENDIAN

On 03/10/2019 08:40, Anders Roxell wrote:
> On Tue, 1 Oct 2019 at 16:04, John Garry <john.garry@...wei.com> wrote:
>>
>> On 26/09/2019 20:30, Anders Roxell wrote:
>>> When building allmodconfig KCONFIG_ALLCONFIG=$(pwd)/arch/arm64/configs/defconfig
>>> CONFIG_CPU_BIG_ENDIAN gets enabled. Which tends not to be what most
>>> people wants.
>>
>> Today allmodconfig does not enable CONFIG_ACPI due to BE config, which
>> is quite unfortunate, I'd say.
>
> right.
>
>>
>>>
>>> Rework so that we disable CONFIG_CPU_BIG_ENDIAN in the defcinfig file so
>>
>> defconfig
>
> thanks.
>
>>
>>> it doesn't get enabled when building allmodconfig kernels. When doing a
>>> 'make savedefconfig' CONFIG_CPU_BIG_ENDIAN will be dropped.
>>
>> So without having to pass KCONFIG_ALLCONFIG or do anything else, what
>> about a config for CONFIG_CPU_LITTLE_ENDIAN instead? I'm not sure if
>> that was omitted for a specific reason.
>
> Oh, I tried to elaborate on the idea in the cover letter, that using
> the defconfig
> as base and then configure the rest as modules is to get a bootable kernel
> that have as many features turned on as possible. That will make it possible
> to run as wide a range of testsuites as possible on a single kernel.
>
> Does that make it clearer ?

Hi Anders,

Yeah, I got the idea.

So when you say "'make savedefconfig' CONFIG_CPU_BIG_ENDIAN will be 
dropped", I don't know what the rules are in terms of resyncing the 
common defconfig (I was under the impression that it's done per release 
cycle by the arm soc maintainers, but can't find evidence as such), but 
your change may be easily lost in this way.

Thanks,
John

>
> Cheers,
> Anders
>
>
>>
>> Thanks,
>> John
>>
>>>
>>> Signed-off-by: Anders Roxell <anders.roxell@...aro.org>
>>> ---
>>>  arch/arm64/configs/defconfig | 1 +
>>>  1 file changed, 1 insertion(+)
>>>
>>> diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
>>> index 878f379d8d84..c9aa6b9ee996 100644
>>> --- a/arch/arm64/configs/defconfig
>>> +++ b/arch/arm64/configs/defconfig
>>> @@ -855,3 +855,4 @@ CONFIG_DEBUG_KERNEL=y
>>>  # CONFIG_SCHED_DEBUG is not set
>>>  CONFIG_MEMTEST=y
>>>  # CONFIG_CMDLINE_FORCE is not set
>>> +# CONFIG_CPU_BIG_ENDIAN is not set
>>>
>>
>>
>
> .
>