[U-Boot] [PATCH v7 1/2] armv8: Support loading 32-bit OS in AArch32 execution state

[Ryan Harkin]

On 4 November 2016 at 02:26, Alison Wang <alison.wang at nxp.com> wrote:
> York,
>
>
>
>                 No, he don’t have my 32-bit kernel image. I am not sure he
> is using 32-bit kernel or 64-bit kernel.
>
>
>
> Ryan,
>
>
>
>                 I am not familiar with the boards you tested,

The FVP Foundation model is free to use from ARM.  The entire software
stack I'm using is available via ARM's portal:

https://community.arm.com/groups/arm-development-platforms


> so I have some
> questions, please help to work with me to find the root cause.
>
>
>
> 1.       Are you loading 32-bit kernel or 64-bit kernel?
>

I'm loading the "standard" 64-bit kernel.  I was using a kernel based off 4.8:

https://git.linaro.org/landing-teams/working/arm/kernel-release.git/log/?h=latest-armlt-20161001

> 2.       Is CONFIG_ARMV8_SWITCH_TO_EL1 defined on these boards?
>

I guess it is for the FVP models, if I grep for it, it's in my configs' .h file:

include/configs/vexpress_aemv8a.h:15:#define CONFIG_ARMV8_SWITCH_TO_EL1

-------------------------------------------------------
#ifdef CONFIG_TARGET_VEXPRESS64_BASE_FVP
#ifndef CONFIG_SEMIHOSTING
#error CONFIG_TARGET_VEXPRESS64_BASE_FVP requires CONFIG_SEMIHOSTING
#endif
#define CONFIG_ARMV8_SWITCH_TO_EL1
#endif
-------------------------------------------------------

But it isn't in my Juno config.


> 3.       Are you using some secure firmware on these boards? In detail, I
> want to know which EL is running on these boards when calling
> armv8_switch_to_el2 in arch/arm/lib/bootm.c. If it is already running in EL2
> when calling armv8_swith_to_el2, the attached patch with PSCI enabled is
> needed.
>

I'm using what ARM consider the "standard" boot flow.  I'm using ARM
Trusted Firmware to boot u-boot which in turn boots an arm64 kernel.

I'd expect my setup to still work after you've added patches to allow
an aarch32 kernel to be booted, but I guess you're changing the boot
path for non-aarch32 kernels also.

Regards,
Ryan.

>
>
>
>
> Best Regards,
>
> Alison Wang
>
>
>
> From: york sun
> Sent: Friday, November 04, 2016 10:04 AM
> To: ryan.harkin at linaro.org
> Cc: Wang Huan <b18965 at freescale.com>; agraf at suse.de; Scott Wood
> <scott.wood at nxp.com>; Stuart Yoder <stuart.yoder at nxp.com>; Leo Li
> <leoyang.li at nxp.com>; fenghua at phytium.com.cn; monstr at monstr.eu;
> thomas.ab at samsung.com; mk7.kang at samsung.com; u-boot at lists.denx.de; Jason Jin
> <jason.jin at nxp.com>; Alison Wang <alison.wang at nxp.com>
>
>
> Subject: Re: [PATCH v7 1/2] armv8: Support loading 32-bit OS in AArch32
> execution state
>
>
>
> Alison,
>
> Does Ryan have your 32-bit kernel image? I think kernel 32-bit doesn't
> support spin table. Please work with Ryan if your PSCI patch is required for
> the test.
>
> York
>
>
>
> -------- Original Message --------
> From: Ryan Harkin <ryan.harkin at linaro.org>
> Sent: Thursday, November 3, 2016 12:17 PM
> To: york sun <york.sun at nxp.com>
> Subject: Re: [PATCH v7 1/2] armv8: Support loading 32-bit OS in AArch32
> execution state
> CC: Alison Wang <b18965 at freescale.com>,agraf at suse.de,Scott Wood
> <scott.wood at nxp.com>,Stuart Yoder <stuart.yoder at nxp.com>,Leo Li
> <leoyang.li at nxp.com>,fenghua at phytium.com.cn,monstr at monstr.eu,thomas.ab at samsung.com,mk7.kang at samsung.com,u-boot at lists.denx.de,Jason
> Jin <jason.jin at nxp.com>,Alison Wang <alison.wang at nxp.com>
>
> Hi York/Alison,
>
> Sorry for not having had time to look at this earlier.
>
>
> On 26 October 2016 at 17:54, york sun <york.sun at nxp.com> wrote:
>> On 10/07/2016 11:56 PM, Alison Wang wrote:
>>> To support loading a 32-bit OS, the execution state will change from
>>> AArch64 to AArch32 when jumping to kernel.
>>>
>>> The architecture information will be got through checking FIT image,
>>> then U-Boot will load 32-bit OS or 64-bit OS automatically.
>>>
>>> Signed-off-by: Ebony Zhu <ebony.zhu at nxp.com>
>>> Signed-off-by: Alison Wang <alison.wang at nxp.com>
>>> Signed-off-by: Chenhui Zhao <chenhui.zhao at nxp.com>
>>> ---
>>> Changes in v7:
>>> - Move the call for armv8_switch_to_el2_m into this patch.
>>>
>>
>> Reviewers,
>>
>> May I have your comment please? I intend to merge this set when the
>> merge window opens.
>>
>
> I've just tested these two patches on ARM's FVP Foundation and AEMv8
> models and ARM's Juno board.
>
> In all cases, with this patchset, the kernel fails to start.  I see a
> continuous reboot, where the kernel starts then immediately resets:
>
> --------------------------------------------------
> Starting kernel ...
>
> resetting ...
> --------------------------------------------------
>
> So I wouldn't want to see these patches merged.
>
> Regards,
> Ryan.