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Re: [PATCH v1 5/5] xen/riscv: map FDT
- To: Oleksii <oleksii.kurochko@xxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Thu, 11 Jul 2024 11:54:03 +0200
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- Cc: Alistair Francis <alistair.francis@xxxxxxx>, Bob Eshleman <bobbyeshleman@xxxxxxxxx>, Connor Davis <connojdavis@xxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Thu, 11 Jul 2024 09:54:17 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 11.07.2024 11:40, Oleksii wrote:
> On Wed, 2024-07-10 at 14:38 +0200, Jan Beulich wrote:
>> On 03.07.2024 12:42, Oleksii Kurochko wrote:
>>> Except mapping of FDT, it is also printing command line passed by
>>> a DTB and initialize bootinfo from a DTB.
>>
>> I'm glad the description isn't empty here. However, ...
>>
>>> --- a/xen/arch/riscv/riscv64/head.S
>>> +++ b/xen/arch/riscv/riscv64/head.S
>>> @@ -41,6 +41,9 @@ FUNC(start)
>>>
>>> jal setup_initial_pagetables
>>>
>>> + mv a0, s1
>>> + jal fdt_map
>>> +
>>> /* Calculate proper VA after jump from 1:1 mapping */
>>> la a0, .L_primary_switched
>>> sub a0, a0, s2
>>
>> ... it could do with clarifying why this needs calling from assembly
>> code. Mapping the FDT clearly looks like something that wants doing
>> from start_xen(), i.e. from C code.
> fdt_map() expected to work while MMU is off as it is using
> setup_initial_mapping() which is working with physical address.
Hmm, interesting. When the MMU is off, what does "map" mean? Yet then
it feels I'm misunderstanding what you're meaning to tell me ...
Jan
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