Re: [PATCH 3/3] xen/arm64/mmu: head: Replace load_paddr with adr_l where appropriate

[Julien Grall <julien@xxxxxxx>]

Hi Michal,

On 21/11/2023 09:45, Michal Orzel wrote:
> Macros load_paddr and adr_l are equivalent when used before the MMU is
> enabled, resulting in obtaining physical address of a symbol. The former
> requires to know the physical offset (PA - VA) and can be used both before
> and after the MMU is enabled. In the spirit of using something only when
> truly necessary, replace all instances of load_paddr with adr_l, except
I don't buy this argument. The advantage with using "load_paddr" is that 
it is pretty clear what you get from the call. With "adr_l" you will 
need to check whether the MMU is on or off.
> in create_table_entry macro. Even though there is currently no use of
> load_paddr after MMU is enabled, this macro used to be call in such a
> context and we can't rule out that it won't happen again.
>
> This way, the logic behind using load_paddr/adr_l is consistent between
> arm32 and arm64, making it easier for developers to determine which one
> to use and when.
Not really. See above. But there is also no documentation stating that 
"load_paddr" should not be used before the MMU is on. And as I said 
above, I find it easier to work with compare to "adr_l".
Cheers,

--
Julien Grall