Re: [PATCH] Arm: drop assertion from page_is_ram_type()

[Julien Grall <julien@xxxxxxx>]

Hi Jan,

On 11/08/2025 14:01, Jan Beulich wrote:
> Its uses in offline_page() and query_page_offline() make it reachable on
> Arm, as long as XEN_SYSCTL_page_offline_op doesn't have any Arm-specific
> code added. It being reachable was even mentioned in the commit
> introducing it, claiming it "clearly shouldn't be called on ARM just
> yet".
So I agree that the function can be reached. But then I don't think the 
function can simply return 0.
The name is too generic enough that someone may end up to use it in 
common code and there will be no signal to the user that the function 
will not properly indicate a RAM page on Arm.
I can think of two possible approaches:

1/ Implement properly page_is_ram_type(). We don't have an e820, but we 
could mimick it using the memory banks we stored.
2/ Rename page_is_ram_type() to page_offlinable() (or similar) so it is 
clear that the common use is for offlining.
The latter might be the simplest.

Cheers,

--
Julien Grall