v3.10 - big endian core support

[Vijay Kilari]

Yes, It works now after using rev16

Regards
Vijay

On Mon, Jul 15, 2013 at 8:20 AM,  <jgq516 at gmail.com> wrote:
> On 07/12/2013 08:00 PM, Ben Dooks wrote:
>>
>> On 12/07/13 12:56, Vijay Kilari wrote:
>>>
>>> On Fri, Jul 12, 2013 at 5:17 PM, Thomas Petazzoni
>>> <thomas.petazzoni at free-electrons.com>  wrote:
>>>>
>>>> Dear Vijay Kilari,
>>>>
>>>> On Fri, 12 Jul 2013 17:09:12 +0530, Vijay Kilari wrote:
>>>>
>>>>>> Ben Dooks has a separate branch on top of this base branch for
>>>>>> big-endian support, that adds atags compat code to convert the ATAGs
>>>>>> data from LE to BE. See the baserock/311/be/atags branch in
>>>>>> git://git.baserock.org/delta/linux. Or
>>>>>>
>>>>>> http://git.baserock.org/cgi-bin/cgit.cgi/delta/linux.git/log/?h=baserock/311/be/atags.
>>>>>
>>>>>
>>>>>   ARM VE TC2 board, enabling CONFIG_THUMB2_KERNEL failed to boot in BE
>>>>> mode
>>>>> It hangs at very early stage of boot
>>>>
>>>>
>>>> Yeah, the Thumb2 code is not supported by Ben Dooks patches, it's part
>>>> of the TODO-list. I think Ben said he would probably not have much time
>>>> to work on this. I might be able to spare some time on this, so just
>>>> let me know if I should start working on this. If I remember correctly,
>>>> it's mainly the fixup_pv_table code that needed some Thumb2/BE love.
>>>
>>>
>>> In fact, I tried with below changes.. still it fails
>>>
>>> diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
>>> index 2de1114..7df64c7 100644
>>> --- a/arch/arm/kernel/head.S
>>> +++ b/arch/arm/kernel/head.S
>>> @@ -592,8 +592,14 @@ __fixup_a_pv_table:
>>>          b       2f
>>>   1:     add     r7, r3
>>>          ldrh    ip, [r7, #2]
>>> +#ifdef CONFIG_CPU_ENDIAN_BE8
>>> +       rev     ip, ip
>>> +#endif
>>
>>
>> Do you need a rev16 here? I think you may have tried
>> reversing the full 32 bits here instead of just the
>> 16bits of instruction that was loaded.
>>
> Thanks Ben, 3.4 kernel booted ok with your suggested modifications.
>
> gjiang at gjiang-desktop:~/work/be-a15$ git diff
> diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
> index 0ad3af8..1a0196c 100644
> --- a/arch/arm/kernel/head.S
> +++ b/arch/arm/kernel/head.S
> @@ -600,8 +600,10 @@ __fixup_a_pv_table:
>
>         b       2f
>  1:     add     r7, r3
>         ldrh    ip, [r7, #2]
> +       rev16   ip, ip @be8
>
>         and     ip, 0x8f00
>         orr     ip, r6  @ mask in offset bits 31-24
> +       rev16   ip, ip @be8
>
>         strh    ip, [r7, #2]
>  2:     cmp     r4, r5
>         ldrcc   r7, [r4], #4    @ use branch for delay slot
>
> root at localhost:~# zcat /proc/config.gz |grep BE8
> CONFIG_CPU_ENDIAN_BE8=y
> CONFIG_CPU_BE8_BOOT_LE=y
> root at localhost:~# zcat /proc/config.gz |grep THUMB
> CONFIG_ARM_THUMB=y
> # CONFIG_ARM_THUMBEE is not set
> CONFIG_THUMB2_KERNEL=y
> CONFIG_THUMB2_AVOID_R_ARM_THM_JUMP11=y
>
>
> Regards,
> Xiao
>
>>>          and     ip, 0x8f00
>>>          orr     ip, r6  @ mask in offset bits 31-24
>>> +#ifdef CONFIG_CPU_ENDIAN_BE8
>>> +       rev     ip, ip
>>> +#endif
>>>          strh    ip, [r7, #2]
>>>   2:     cmp     r4, r5
>>>          ldrcc   r7, [r4], #4    @ use branch for delay slot
>>>
>>>>
>>>> Will, is getting Thumb2 working a requirement to get the BE support
>>>> merged, or can we for now make the BE option depends on !THUMB2_KERNEL ?
>>>>
>>>> Thanks!
>>>>
>>>> Thomas
>>>> --
>>>> Thomas Petazzoni, Free Electrons
>>>> Kernel, drivers, real-time and embedded Linux
>>>> development, consulting, training and support.
>>>> http://free-electrons.com
>>
>>
>>
>