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Re: [PATCH] calibrate_tsc(): use the Stall() EFI boot service on GRUB_MA
From: |
Andrei Borzenkov |
Subject: |
Re: [PATCH] calibrate_tsc(): use the Stall() EFI boot service on GRUB_MACHINE_EFI |
Date: |
Wed, 26 Nov 2014 16:42:10 +0300 |
On Wed, Nov 26, 2014 at 11:59 AM, Laszlo Ersek <address@hidden> wrote:
> HyperV Gen2 virtual machines have no PIT; guest code should rely on UEFI
> services instead.
>
Your patch affects all EFI systems; is it possible to detect HyperV at
this level?
> 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 <address@hidden>
> ---
>
> 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
>
>
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