Re: [PATCH v2] ARM: boot: Obtain start of physical memory from DTB

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19.03.2020 12:25, Russell King - ARM Linux admin пишет:
> On Thu, Mar 19, 2020 at 04:11:00AM +0300, Dmitry Osipenko wrote:
>> 25.02.2020 14:40, Geert Uytterhoeven пишет:
>>> Hi Marek,
>>>
>>> On Tue, Feb 25, 2020 at 12:24 PM Marek Szyprowski
>>> <m.szyprowski@xxxxxxxxxxx> wrote:
>>>> On 27.01.2020 15:07, Geert Uytterhoeven wrote:
>>>>> Currently, the start address of physical memory is obtained by masking
>>>>> the program counter with a fixed mask of 0xf8000000.  This mask value
>>>>> was chosen as a balance between the requirements of different platforms.
>>>>> However, this does require that the start address of physical memory is
>>>>> a multiple of 128 MiB, precluding booting Linux on platforms where this
>>>>> requirement is not fulfilled.
>>>>>
>>>>> Fix this limitation by obtaining the start address from the DTB instead,
>>>>> if available (either explicitly passed, or appended to the kernel).
>>>>> Fall back to the traditional method when needed.
>>>>>
>>>>> This allows to boot Linux on r7s9210/rza2mevb using the 64 MiB of SDRAM
>>>>> on the RZA2MEVB sub board, which is located at 0x0C000000 (CS3 space),
>>>>> i.e. not at a multiple of 128 MiB.
>>>>>
>>>>> Suggested-by: Nicolas Pitre <nico@xxxxxxxxxxx>
>>>>> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
>>>>> Reviewed-by: Nicolas Pitre <nico@xxxxxxxxxxx>
>>>>> ---
>>>>> Against arm/for-next.
>>>>
>>>> This patch landed recently in linux-next. It breaks legacy booting from
>>>> the zImage + appended DT + cmdline/memory info provided via ATAGs. I
>>>> will debug it further once I find some spare time. What I noticed so
>>>> far, the cmdline/memory info is not read from the ATAGs, only the values
>>>> provided via appended DT are used.
>>>
>>> Oops, something happening like this was one of my biggest worries when
>>> posting this patch... Sorry for the breakage.
>>>
>>> IIUIC, the kernel still boots, but just doesn't use the info passed by ATAGs?
>>>
>>> I'll have a closer look later today.
>>> In the mean time, I've sent some debug code I used when developing
>>> this patch, which may be useful, hopefully.
>>
>> Hello,
>>
>> NVIDIA Tegra is also affected by this patch. A week ago an updated
>> version of the patch was pushed into linux-next and now machine doesn't
>> boot at all.
>>
>> I couldn't find v3 on the ML, so replying to the v2. Please take a look
>> and fix the problem, or revert/drop the offending patch, thanks in advance.
> 
> I'll drop the patch. It's clear that this is going to be difficult,
> so I would ask you to test the next version, rather than waiting for
> it to appear in linux-next.

Thank you very much! I'll be happy to try v4, please feel free to CC me.



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