Re: [PATCH v2 0/7] KSTATE: a mechanism to migrate some part of the kernel state across kexec

[Cong Wang]

Hi Andrey,

On Mon, Mar 10, 2025 at 5:04 AM Andrey Ryabinin <arbn@xxxxxxxxxxxxxxx> wrote:
>     Each driver/subsystem has to solve this problem in their own way.
>     Also if we use fdt properties for individual fields, that might be wastefull
>     in terms of used memory, as these properties use strings as keys.
>
>    While with KSTATE solves the same problem in more elegant way, with this:
>         struct kstate_description a_state = {
>                 .name = "a_struct",
>                 .version_id = 1,
>                 .id = KSTATE_TEST_ID,
>                 .state_list = LIST_HEAD_INIT(test_state.state_list),
>                 .fields = (const struct kstate_field[]) {
>                         KSTATE_BASE_TYPE(i, struct a, int),
>                         KSTATE_BASE_TYPE(s, struct a, char [10]),
>                         KSTATE_POINTER(p_ulong, struct a),
>                         KSTATE_PAGE(page, struct a),
>                         KSTATE_END_OF_LIST()
>                 },
>         };

Hmm, this still requires manual efforts to implement this, so potentially
a lot of work given how many drivers we have in-tree.

And those KSTATE_* stuffs look a lot similar to BTF:
https://docs.kernel.org/bpf/btf.html

So, any possibility to reuse BTF here? Note, BTF is automatically
generated by pahole, no manual effort is required.

Regards,
Cong Wang