ACPI or MP config

[gerryg400]

Hi, I just tested my kernel on a Quad core, hyperthreaded Xeon machine and it failed to load because this machine doesn't have MP config tables. It only has ACPI tables. I guess I know what I'll be working on tonight!!!

Anyway, some machines seem to have both MP config tables and ACPI tables. If both exist which one should I read ?

tia

- gerryg400

[quok]

Read both. Rely on ACPI first, and use the MP config tables as a fallback.

Of course, just because both exist doesn't mean that they're both correct, either. The ACPI tables may be broke in some way, in which case you'd again want to fall back on the MP config tables. Just make sure you verify checksums for all tables and such.

[gerryg400]

Quok,

Thanks, I'll go with that. Read ACPI first then MP config.

Continuing, currently I get my memory config from grub multiboot structure. Is that the best way. I think I can also see the memory map in the MP config tables. Which should I use ?

- gerryg400

[bewing]

Use the grub multiboot header. It comes from Int15h eax=e820 -- there is no way any other table could get more accurate than the e820 info. And the MP tables are technically obsolete -- so you shouldn't rely on anything from them, unless you have to. That is, only use MP table info as a fallback, after other sources fail.

[gerryg400]

Thanks bewing.so it's

Code: Select all

void get_system_info() {

    mem_config = read_multiboot_tables();
    if (acpi_found()) {
        other_config = read_acpi_tables();
    }
    else if (mp_table_found()) {
        other_config = read_mp_config();
    }
    else {
        other_config = manual_config();
    }
}

- gerryg400