Re: [PATCH] calibrate_tsc(): use the Stall() EFI boot service on GRUB_MACHINE_EFI

[Andrei Borzenkov <arvidjaar@gmail.com>]

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В Fri, 28 Nov 2014 21:25:30 +0200
Vladimir 'φ-coder/phcoder' Serbinenko <phcoder@gmail.com> пишет:

> On 26.11.2014 10:59, Laszlo Ersek wrote:
> > HyperV Gen2 virtual machines have no PIT; guest code should rely on UEFI
> > services instead.
> > 
> > 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 <lersek@redhat.com>
> I don't like to be using any additional EFI function. I prefer to use
> pmtimer as I did in my other patch. Is pmtimer available on hyperv?

It was tested on Hyper-V v2 in https://savannah.gnu.org/bugs/?42944. I
have no idea if it is available on Hyper-V v1.

> > ---
> > 
> > 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);
> > 
> 
> 


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