372 lines
12 KiB
Diff
372 lines
12 KiB
Diff
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From d47c03e078f39034d1843dfe8a84aedff40638ba Mon Sep 17 00:00:00 2001
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From: Vladimir 'phcoder' Serbinenko <phcoder@gmail.com>
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Date: Sun, 10 Mar 2013 17:45:38 +0100
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Subject: [PATCH 200/364] Avoid costly 64-bit division in
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grub_get_time_ms on most platforms.
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---
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ChangeLog | 4 ++++
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grub-core/Makefile.am | 14 ++++++------
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grub-core/Makefile.core.def | 3 ---
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grub-core/kern/i386/pc/init.c | 6 +++---
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grub-core/kern/i386/pit.c | 49 ------------------------------------------
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grub-core/kern/i386/tsc.c | 50 +++++++++++++++++++++++++++++++++----------
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grub-core/loader/i386/xnu.c | 28 +++++++++++++-----------
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include/grub/i386/pc/time.h | 5 -----
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include/grub/i386/pit.h | 2 --
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include/grub/i386/tsc.h | 2 ++
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10 files changed, 70 insertions(+), 93 deletions(-)
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delete mode 100644 grub-core/kern/i386/pit.c
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diff --git a/ChangeLog b/ChangeLog
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index c604d8d..bc51ae9 100644
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--- a/ChangeLog
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+++ b/ChangeLog
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@@ -1,5 +1,9 @@
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2013-03-10 Vladimir Serbinenko <phcoder@gmail.com>
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+ Avoid costly 64-bit division in grub_get_time_ms on most platforms.
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+
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+2013-03-10 Vladimir Serbinenko <phcoder@gmail.com>
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+
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* grub-core/fs/fshelp.c (grub_fshelp_log2blksize): Remove now unused
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function.
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diff --git a/grub-core/Makefile.am b/grub-core/Makefile.am
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index 9cb14e2..221466b 100644
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--- a/grub-core/Makefile.am
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+++ b/grub-core/Makefile.am
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@@ -98,29 +98,29 @@ if COND_i386_pc
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KERNEL_HEADER_FILES += $(top_builddir)/include/grub/machine/kernel.h
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KERNEL_HEADER_FILES += $(top_builddir)/include/grub/machine/pxe.h
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KERNEL_HEADER_FILES += $(top_builddir)/include/grub/machine/int.h
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-KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/pit.h
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+KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/tsc.h
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endif
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if COND_i386_efi
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KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/efi/efi.h
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KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/efi/disk.h
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-KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/pit.h
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+KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/tsc.h
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KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/pci.h
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endif
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if COND_i386_coreboot
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-KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/pit.h
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+KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/tsc.h
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KERNEL_HEADER_FILES += $(top_builddir)/include/grub/i386/pc/int.h
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endif
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if COND_i386_multiboot
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-KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/pit.h
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+KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/tsc.h
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KERNEL_HEADER_FILES += $(top_builddir)/include/grub/i386/pc/int.h
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endif
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if COND_i386_qemu
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KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/pci.h
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-KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/pit.h
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+KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/tsc.h
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endif
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if COND_i386_ieee1275
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@@ -128,13 +128,13 @@ KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/ieee1275/ieee1275.h
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KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/terminfo.h
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KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/extcmd.h
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KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/lib/arg.h
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-KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/pit.h
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+KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/tsc.h
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endif
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if COND_x86_64_efi
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KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/efi/efi.h
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KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/efi/disk.h
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-KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/pit.h
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+KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/i386/tsc.h
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KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/pci.h
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endif
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diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
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index 93ff2a8..3bcf662 100644
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--- a/grub-core/Makefile.core.def
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+++ b/grub-core/Makefile.core.def
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@@ -102,7 +102,6 @@ kernel = {
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noemu_nodist = symlist.c;
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- i386_pc = kern/generic/rtc_get_time_ms.c;
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mips = kern/generic/rtc_get_time_ms.c;
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ieee1275 = disk/ieee1275/ofdisk.c;
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@@ -123,8 +122,6 @@ kernel = {
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i386_coreboot_multiboot_qemu = kern/i386/coreboot/init.c;
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i386_coreboot_multiboot_qemu = term/i386/pc/vga_text.c;
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- x86 = kern/i386/pit.c;
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-
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efi = disk/efi/efidisk.c;
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efi = kern/efi/efi.c;
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efi = kern/efi/init.c;
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diff --git a/grub-core/kern/i386/pc/init.c b/grub-core/kern/i386/pc/init.c
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index 730e04a..5b68504 100644
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--- a/grub-core/kern/i386/pc/init.c
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+++ b/grub-core/kern/i386/pc/init.c
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@@ -52,8 +52,8 @@ void (*grub_pc_net_config) (char **device, char **path);
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* return the real time in ticks, of which there are about
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* 18-20 per second
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*/
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-grub_uint32_t
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-grub_get_rtc (void)
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+grub_uint64_t
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+grub_rtc_get_time_ms (void)
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{
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struct grub_bios_int_registers regs;
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@@ -61,7 +61,7 @@ grub_get_rtc (void)
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regs.flags = GRUB_CPU_INT_FLAGS_DEFAULT;
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grub_bios_interrupt (0x1a, ®s);
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- return (regs.ecx << 16) | (regs.edx & 0xffff);
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+ return ((regs.ecx << 16) | (regs.edx & 0xffff)) * 55ULL;
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}
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void
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diff --git a/grub-core/kern/i386/pit.c b/grub-core/kern/i386/pit.c
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deleted file mode 100644
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index 092481a..0000000
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--- a/grub-core/kern/i386/pit.c
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+++ /dev/null
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@@ -1,49 +0,0 @@
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-/*
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- * GRUB -- GRand Unified Bootloader
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- * Copyright (C) 2008 Free Software Foundation, Inc.
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- *
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- * GRUB is free software: you can redistribute it and/or modify
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- * it under the terms of the GNU General Public License as published by
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- * the Free Software Foundation, either version 3 of the License, or
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- * (at your option) any later version.
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- *
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- * GRUB is distributed in the hope that it will be useful,
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- * but WITHOUT ANY WARRANTY; without even the implied warranty of
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- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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- * GNU General Public License for more details.
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- *
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- * You should have received a copy of the GNU General Public License
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- * along with GRUB. If not, see <http://www.gnu.org/licenses/>.
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- */
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-
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-#include <grub/types.h>
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-#include <grub/i386/io.h>
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-#include <grub/i386/pit.h>
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-
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-void
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-grub_pit_wait (grub_uint16_t tics)
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-{
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- /* Disable timer2 gate and speaker. */
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- grub_outb (grub_inb (GRUB_PIT_SPEAKER_PORT)
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- & ~ (GRUB_PIT_SPK_DATA | GRUB_PIT_SPK_TMR2),
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- GRUB_PIT_SPEAKER_PORT);
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-
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- /* Set tics. */
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- grub_outb (GRUB_PIT_CTRL_SELECT_2 | GRUB_PIT_CTRL_READLOAD_WORD,
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- GRUB_PIT_CTRL);
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- grub_outb (tics & 0xff, GRUB_PIT_COUNTER_2);
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- grub_outb (tics >> 8, GRUB_PIT_COUNTER_2);
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-
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- /* Enable timer2 gate, keep speaker disabled. */
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- grub_outb ((grub_inb (GRUB_PIT_SPEAKER_PORT) & ~ GRUB_PIT_SPK_DATA)
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- | GRUB_PIT_SPK_TMR2,
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- GRUB_PIT_SPEAKER_PORT);
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-
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- /* Wait. */
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- while ((grub_inb (GRUB_PIT_SPEAKER_PORT) & GRUB_PIT_SPK_TMR2_LATCH) == 0x00);
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-
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- /* Disable timer2 gate and speaker. */
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- grub_outb (grub_inb (GRUB_PIT_SPEAKER_PORT)
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- & ~ (GRUB_PIT_SPK_DATA | GRUB_PIT_SPK_TMR2),
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- GRUB_PIT_SPEAKER_PORT);
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-}
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diff --git a/grub-core/kern/i386/tsc.c b/grub-core/kern/i386/tsc.c
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index c4645f0..9efd633 100644
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--- a/grub-core/kern/i386/tsc.c
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+++ b/grub-core/kern/i386/tsc.c
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@@ -25,37 +25,66 @@
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#include <grub/misc.h>
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#include <grub/i386/tsc.h>
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#include <grub/i386/pit.h>
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+#include <grub/cpu/io.h>
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/* This defines the value TSC had at the epoch (that is, when we calibrated it). */
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static grub_uint64_t tsc_boot_time;
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-/* Calibrated TSC rate. (In TSC ticks per millisecond.) */
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-static grub_uint64_t tsc_ticks_per_ms;
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+/* Calibrated TSC rate. (In ms per 2^32 ticks) */
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+/* We assume that the tick is less than 1 ms and hence this value fits
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+ in 32-bit. */
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+grub_uint32_t grub_tsc_rate;
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+static void
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+grub_pit_wait (grub_uint16_t tics)
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+{
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+ /* Disable timer2 gate and speaker. */
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+ grub_outb (grub_inb (GRUB_PIT_SPEAKER_PORT)
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+ & ~ (GRUB_PIT_SPK_DATA | GRUB_PIT_SPK_TMR2),
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+ GRUB_PIT_SPEAKER_PORT);
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+
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+ /* Set tics. */
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+ grub_outb (GRUB_PIT_CTRL_SELECT_2 | GRUB_PIT_CTRL_READLOAD_WORD,
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+ GRUB_PIT_CTRL);
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+ grub_outb (tics & 0xff, GRUB_PIT_COUNTER_2);
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+ grub_outb (tics >> 8, GRUB_PIT_COUNTER_2);
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+
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+ /* Enable timer2 gate, keep speaker disabled. */
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+ grub_outb ((grub_inb (GRUB_PIT_SPEAKER_PORT) & ~ GRUB_PIT_SPK_DATA)
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+ | GRUB_PIT_SPK_TMR2,
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+ GRUB_PIT_SPEAKER_PORT);
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+
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+ /* Wait. */
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+ while ((grub_inb (GRUB_PIT_SPEAKER_PORT) & GRUB_PIT_SPK_TMR2_LATCH) == 0x00);
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+
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+ /* Disable timer2 gate and speaker. */
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+ grub_outb (grub_inb (GRUB_PIT_SPEAKER_PORT)
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+ & ~ (GRUB_PIT_SPK_DATA | GRUB_PIT_SPK_TMR2),
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+ GRUB_PIT_SPEAKER_PORT);
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+}
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grub_uint64_t
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grub_tsc_get_time_ms (void)
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{
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- return tsc_boot_time + grub_divmod64 (grub_get_tsc (), tsc_ticks_per_ms, 0);
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-}
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+ grub_uint64_t a = grub_get_tsc () - tsc_boot_time;
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+ grub_uint64_t ah = a >> 32;
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+ grub_uint64_t al = a & 0xffffffff;
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-
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-/* How many RTC ticks to use for calibration loop. (>= 1) */
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-#define CALIBRATION_TICKS 2
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+ return ((al * grub_tsc_rate) >> 32) + ah * grub_tsc_rate;
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+}
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/* Calibrate the TSC based on the RTC. */
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static void
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calibrate_tsc (void)
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{
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/* First calibrate the TSC rate (relative, not absolute time). */
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- grub_uint64_t start_tsc;
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grub_uint64_t end_tsc;
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- start_tsc = grub_get_tsc ();
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+ tsc_boot_time = grub_get_tsc ();
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grub_pit_wait (0xffff);
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end_tsc = grub_get_tsc ();
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- tsc_ticks_per_ms = grub_divmod64 (end_tsc - start_tsc, 55, 0);
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+ grub_tsc_rate = grub_divmod64 ((55ULL << 32), end_tsc - tsc_boot_time, 0);
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}
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void
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@@ -63,7 +92,6 @@ grub_tsc_init (void)
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{
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if (grub_cpu_is_tsc_supported ())
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{
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- tsc_boot_time = grub_get_tsc ();
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calibrate_tsc ();
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grub_install_get_time_ms (grub_tsc_get_time_ms);
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}
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diff --git a/grub-core/loader/i386/xnu.c b/grub-core/loader/i386/xnu.c
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index 4e5ce09..497529b 100644
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--- a/grub-core/loader/i386/xnu.c
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+++ b/grub-core/loader/i386/xnu.c
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@@ -125,9 +125,6 @@ guessfsb (void)
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{
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const grub_uint64_t sane_value = 100000000;
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grub_uint32_t manufacturer[3], max_cpuid, capabilities, msrlow;
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- grub_uint64_t start_tsc;
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- grub_uint64_t end_tsc;
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- grub_uint64_t tsc_ticks_per_ms;
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if (! grub_cpu_is_cpuid_supported ())
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return sane_value;
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@@ -192,14 +189,6 @@ guessfsb (void)
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if (! (capabilities & (1 << 7)))
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return sane_value;
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- /* Calibrate the TSC rate. */
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-
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- start_tsc = grub_get_tsc ();
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- grub_pit_wait (0xffff);
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- end_tsc = grub_get_tsc ();
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-
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- tsc_ticks_per_ms = grub_divmod64 (end_tsc - start_tsc, 55, 0);
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-
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/* Read the multiplier. */
|
||
|
|
asm volatile ("movl $0x198, %%ecx\n"
|
||
|
|
"rdmsr"
|
||
|
|
@@ -207,8 +196,21 @@ guessfsb (void)
|
||
|
|
:
|
||
|
|
: "%ecx", "%eax");
|
||
|
|
|
||
|
|
- return grub_divmod64 (2000 * tsc_ticks_per_ms,
|
||
|
|
- ((msrlow >> 7) & 0x3e) + ((msrlow >> 14) & 1), 0);
|
||
|
|
+ grub_uint64_t v;
|
||
|
|
+ grub_uint32_t r;
|
||
|
|
+
|
||
|
|
+ /* (2000ULL << 32) / grub_tsc_rate */
|
||
|
|
+ /* Assumption: TSC frequency is over 2 MHz. */
|
||
|
|
+ v = 0xffffffff / grub_tsc_rate;
|
||
|
|
+ v *= 2000;
|
||
|
|
+ /* v is at most 2000 off from (2000ULL << 32) / grub_tsc_rate.
|
||
|
|
+ Since grub_tsc_rate < 2^32/2^11=2^21, so no overflow.
|
||
|
|
+ */
|
||
|
|
+ r = (2000ULL << 32) - v * grub_tsc_rate;
|
||
|
|
+ v += r / grub_tsc_rate;
|
||
|
|
+
|
||
|
|
+ return grub_divmod64 (v, ((msrlow >> 7) & 0x3e) | ((msrlow >> 14) & 1),
|
||
|
|
+ 0);
|
||
|
|
}
|
||
|
|
|
||
|
|
struct property_descriptor
|
||
|
|
diff --git a/include/grub/i386/pc/time.h b/include/grub/i386/pc/time.h
|
||
|
|
index ba227ca..e93320f 100644
|
||
|
|
--- a/include/grub/i386/pc/time.h
|
||
|
|
+++ b/include/grub/i386/pc/time.h
|
||
|
|
@@ -21,9 +21,4 @@
|
||
|
|
|
||
|
|
#include <grub/symbol.h>
|
||
|
|
|
||
|
|
-#define GRUB_TICKS_PER_SECOND 18
|
||
|
|
-
|
||
|
|
-/* Return the real time in ticks. */
|
||
|
|
-grub_uint32_t grub_get_rtc (void);
|
||
|
|
-
|
||
|
|
#endif /* ! KERNEL_MACHINE_TIME_HEADER */
|
||
|
|
diff --git a/include/grub/i386/pit.h b/include/grub/i386/pit.h
|
||
|
|
index e1c92cd..4bd49d4 100644
|
||
|
|
--- a/include/grub/i386/pit.h
|
||
|
|
+++ b/include/grub/i386/pit.h
|
||
|
|
@@ -100,6 +100,4 @@ enum
|
||
|
|
GRUB_PIT_CTRL_COUNT_BCD = 0x01 /* 4-decade BCD counter. */
|
||
|
|
};
|
||
|
|
|
||
|
|
-void EXPORT_FUNC(grub_pit_wait) (grub_uint16_t tics);
|
||
|
|
-
|
||
|
|
#endif /* ! KERNEL_CPU_PIT_HEADER */
|
||
|
|
diff --git a/include/grub/i386/tsc.h b/include/grub/i386/tsc.h
|
||
|
|
index 2442d7e..d25d0e3 100644
|
||
|
|
--- a/include/grub/i386/tsc.h
|
||
|
|
+++ b/include/grub/i386/tsc.h
|
||
|
|
@@ -137,5 +137,7 @@ grub_cpu_is_tsc_supported (void)
|
||
|
|
|
||
|
|
void grub_tsc_init (void);
|
||
|
|
grub_uint64_t grub_tsc_get_time_ms (void);
|
||
|
|
+/* In ms per 2^32 ticks. */
|
||
|
|
+extern grub_uint32_t EXPORT_VAR(grub_tsc_rate);
|
||
|
|
|
||
|
|
#endif /* ! KERNEL_CPU_TSC_HEADER */
|
||
|
|
--
|
||
|
|
1.8.1.4
|
||
|
|
|