Re: [PATCH v7] RISC-V: enable XIP

David Hildenbrand
2021-04-09T12:46:30Z

>>> Also, will that memory properly be exposed in the resource tree as
>>> System RAM (e.g., /proc/iomem) ? Otherwise some things (/proc/kcore)
>>> won't work as expected - the kernel won't be included in a dump.
>
> Do we really need a XIP kernel to included in kdump?
> And does not it sound weird to expose flash as System RAM in /proc/iomem? ;-)

See my other mail, maybe we actually want something different.

>
>> I have just checked and it does not appear in /proc/iomem.
>>
>> Ok your conclusion would be to have struct page, I'm going to implement this
>> version then using memblock as you described.
>
> I'm not sure this is required. With XIP kernel text never gets into RAM, so
> it does not seem to require struct page.
>
> XIP by definition has some limitations relatively to "normal" operation,
> so lack of kdump could be one of them.

I agree.

>
> I might be wrong, but IMHO, artificially creating a memory map for part of
> flash would cause more problems in the long run.

Can you elaborate?

>
> BTW, how does XIP account the kernel text on other architectures that
> implement it?

Interesting point, I thought XIP would be something new on RISC-V (well,
at least to me :) ). If that concept exists already, we better mimic
what existing implementations do.

--
Thanks,

David / dhildenb