On 11/26/14 14:42, Andrei Borzenkov wrote: > On Wed, Nov 26, 2014 at 11:59 AM, Laszlo Ersek <ler...@redhat.com> wrote: >> HyperV Gen2 virtual machines have no PIT; guest code should rely on UEFI >> services instead. >> > > Your patch affects all EFI systems;
Which is intended -- No UEFI system guarantees the presence of the PIT, but they are all required to provide the gBS->Stall() boot service. So, the current PIT-based code may or may not work on a random UEFI system (and in fact it happens to fail in HyperV Gen2 guests, because those actually exploit the no-legacy liberty provided by the UEFI spec), but the proposed replacement (== rely on gBS->Stall()) *must* work on all UEFI systems. For example, the patch works on top of OVMF in a QEMU/KVM guest too (== different UEFI firmware implementation and different hypervisor). > is it possible to detect HyperV at > this level? Perhaps, but that should definitely not be done. Enlightenment is not the way to go about this. Thanks Laszlo >> RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1150698 >> RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1160128 >> Signed-off-by: Laszlo Ersek <ler...@redhat.com> >> --- >> >> Notes: >> Please note that I'm not subscribed to the list. >> >> grub-core/kern/i386/tsc.c | 20 ++++++++++++++++---- >> 1 file changed, 16 insertions(+), 4 deletions(-) >> >> diff --git a/grub-core/kern/i386/tsc.c b/grub-core/kern/i386/tsc.c >> index 3a4cae6..e499648 100644 >> --- a/grub-core/kern/i386/tsc.c >> +++ b/grub-core/kern/i386/tsc.c >> @@ -26,9 +26,14 @@ >> #include <grub/i386/tsc.h> >> #include <grub/i386/cpuid.h> >> #ifdef GRUB_MACHINE_XEN >> -#include <grub/xen.h> >> +# include <grub/xen.h> >> #else >> -#include <grub/i386/pit.h> >> +# ifdef GRUB_MACHINE_EFI >> +# include <grub/efi/efi.h> >> +# include <grub/efi/api.h> >> +# else >> +# include <grub/i386/pit.h> >> +# endif >> #endif >> #include <grub/cpu/io.h> >> >> @@ -72,8 +77,14 @@ grub_cpu_is_tsc_supported (void) >> #ifndef GRUB_MACHINE_XEN >> >> static void >> -grub_pit_wait (grub_uint16_t tics) >> +grub_stall (grub_uint16_t tics) >> { >> +# ifdef GRUB_MACHINE_EFI >> + grub_uint64_t microseconds; >> + >> + microseconds = (grub_uint64_t)tics * 1000 * 1000 * 3 / 3579545; >> + efi_call_1 (grub_efi_system_table->boot_services->stall, microseconds); >> +# else >> /* Disable timer2 gate and speaker. */ >> grub_outb (grub_inb (GRUB_PIT_SPEAKER_PORT) >> & ~ (GRUB_PIT_SPK_DATA | GRUB_PIT_SPK_TMR2), >> @@ -97,6 +108,7 @@ grub_pit_wait (grub_uint16_t tics) >> grub_outb (grub_inb (GRUB_PIT_SPEAKER_PORT) >> & ~ (GRUB_PIT_SPK_DATA | GRUB_PIT_SPK_TMR2), >> GRUB_PIT_SPEAKER_PORT); >> +# endif >> } >> #endif >> >> @@ -119,7 +131,7 @@ calibrate_tsc (void) >> grub_uint64_t end_tsc; >> >> tsc_boot_time = grub_get_tsc (); >> - grub_pit_wait (0xffff); >> + grub_stall (0xffff); >> end_tsc = grub_get_tsc (); >> >> grub_tsc_rate = grub_divmod64 ((55ULL << 32), end_tsc - tsc_boot_time, 0); >> -- >> 1.8.3.1 >> >> >> _______________________________________________ >> Grub-devel mailing list >> Grub-devel@gnu.org >> https://lists.gnu.org/mailman/listinfo/grub-devel _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
