On 04/09/2016 18:14, Konstantin Belousov wrote: > On Sun, Sep 04, 2016 at 11:19:16AM +0300, Andriy Gapon wrote: >> Kostik, I see one strange thing which is common to both successful and >> unsuccessful configurations. All "SMP: Added CPU..." lines have "AP" in >> them. >> It seems like the platform does not tell explicitly tell which CPU is the >> BSP, >> see cpu_add() function. This can break quite a few assumption. And I am not >> even sure how the successful scenario works. >> Ah... I see that there is a backup code in cpu_mp_start() where boot_cpu_id >> is >> set based on the current CPU's Local APIC ID. I suspect then that this >> information is incorrect in the failing case. >> > Well, there is no easy way to read the LAPIC Id of BSP before LAPICs > are initialized. BIOS might reprogram LAPIC Ids, so reading from > CPUID[1].EBX[31:24] might return incorrect data. Even more incorrect > it might be in the x2APIC state, since 8 bits are not enough for 32bit > x2APIC Id.
Hmm, I am not sure how what you are saying here is relevant to the problem. I believe that cpu_mp_start() is executed (on the BSP) after the BSP's LAPIC is initialized. So, the code should just work. My theory was that the BSP's LAPIC ID was incorrectly programmed by BIOS (firmware). -- Andriy Gapon _______________________________________________ freebsd-stable@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
