On 01/27/17 15:57, Laszlo Ersek wrote: > On 01/27/17 15:27, Kevin O'Connor wrote: >> On Fri, Jan 27, 2017 at 02:18:39AM +0100, Filippo Sironi wrote: >>> When running Linux on an Intel machine with a commodity BIOS, CPUs are >>> numbered starting from 0 and the first half refers to the first logical >>> CPU on each core while the second half refers to the second logical CPU >>> on each core. >>> As an example, on machine with 2 sockets, 4 cores per socket, and 2 >>> logical CPUs per core, CPUs would be numbered: >>> >>> * 0 1 2 3 - first logical CPU on each core of socket 0 >>> * 4 5 6 7 - first logical CPU on each core of socket 1 >>> * 8 9 10 11 - second logical CPU on each core of socket 0 >>> * 12 13 14 15 - second logical CPU on each core of socket 1 >>> >>> With seabios (prior to this patch), CPU 0 would be the first logical CPU >>> on core 0 of socket 0, CPU 1 would be the second logical CPU on core 0 >>> of socket 0, and so on. >>> This is due to the fact that processor_id and local_apic_id are assigned >>> with the same value when building MADT. >>> >>> Exhaust the most-significant 7 bits of the 8-bit APIC ID and then come >>> back to the least-significant bit when assigning local_apic_id, since >>> the least-significant bit identifies the second logical CPU on a core. >>> >>> If HTT isn't available, keep the previous behavior. >>> >>> Signed-off-by: Filippo Sironi <sir...@amazon.de> >>> --- >>> src/fw/acpi.c | 42 +++++++++++++++++++++++++++++++++++++++++- >>> 1 file changed, 41 insertions(+), 1 deletion(-) >>> >>> diff --git a/src/fw/acpi.c b/src/fw/acpi.c >>> index 8bc2ca6..864c247 100644 >>> --- a/src/fw/acpi.c >>> +++ b/src/fw/acpi.c >> >> The acpi.c code in seabios is deprecated. With all recent version of >> qemu/kvm the acpi tables are obtained from qemu. So, if there is a >> desired change to the tables then a patch should be made for qemu. > > QEMU constructs minimal / condensed APIC IDs so that they precisely > correspond to the socket / core / thread hierarchy requested on the > command line. If I remember correctly, the algorithm was implemented > directly from Intel's MP spec. If the APIC IDs in the guest don't look > as desired, I think the -smp option might have to be tweaked.
... by that I attempted (and failed) to say that the error is likely on the concrete QEMU command line, not in the code. > > I also seem to recall that this spec-adherent behavior could be machine > type dependent (i.e., unavailable before a specific machine type). The > machtypes not conforming to it should be ancient IMO. > > CC'ing Eduardo and Igor. > > Thanks > Laszlo > _______________________________________________ SeaBIOS mailing list SeaBIOS@seabios.org https://www.coreboot.org/mailman/listinfo/seabios
