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

["Vladimir 'φ-coder/phcoder' Serbinenko" <phcoder@gmail.com>]

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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?
> ---
> 
> 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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