hw: calibrate Local APIC via ACPI timer

Upto now, bootstrap used the Programmable Interval Timer to set a suitable divider and determine the frequency of the Local APIC. The PIT is not available on recent x86_64 hardware anymore. Move Local APIC calibration to bootstrap and use the ACPI timer as a reference. Clean up hw's timer implementation a little and disable the PIT in bootstrap. Fixes #5215
2026-01-21 12:32:56 +01:00 · 2025-01-09 11:31:42 +01:00
parent 103d03b590
commit 8bdddbd46a
22 changed files with 176 additions and 155 deletions
--- a/repos/base-hw/src/core/spec/x86_64/port_io.h
+++ b/repos/base-hw/src/core/spec/x86_64/port_io.h
@@ -11,13 +11,14 @@
 * under the terms of the GNU Affero General Public License version 3.
 */

-#ifndef _CORE__SPEC__X86_64__PORT_IO_H_
-#define _CORE__SPEC__X86_64__PORT_IO_H_
+#ifndef _INCLUDE__SPEC__X86_64__PORT_IO_H_
+#define _INCLUDE__SPEC__X86_64__PORT_IO_H_

-/* core includes */
-#include <types.h>
+#include <base/fixed_stdint.h>

-namespace Core {
+namespace Hw {
+	using Genode::uint8_t;
+	using Genode::uint16_t;

 	/**
 	 * Read byte from I/O port
@@ -38,4 +39,4 @@ namespace Core {
 	}
 }

-#endif /* _CORE__SPEC__X86_64__PORT_IO_H_ */
+#endif /* _INCLUDE__SPEC__X86_64__PORT_IO_H_ */
--- a/repos/base-hw/lib/mk/spec/x86_64/core-hw-pc.mk
+++ b/repos/base-hw/lib/mk/spec/x86_64/core-hw-pc.mk
@@ -24,7 +24,7 @@ SRC_CC += spec/x86_64/virtualization/kernel/svm.cc
 SRC_CC += spec/x86_64/virtualization/kernel/vmx.cc
 SRC_CC += kernel/lock.cc
 SRC_CC += spec/x86_64/pic.cc
-SRC_CC += spec/x86_64/pit.cc
+SRC_CC += spec/x86_64/timer.cc
 SRC_CC += spec/x86_64/kernel/thread_exception.cc
 SRC_CC += spec/x86_64/platform_support.cc
 SRC_CC += spec/x86_64/virtualization/platform_services.cc
--- a/repos/base-hw/src/bootstrap/spec/x86_64/platform.cc
+++ b/repos/base-hw/src/bootstrap/spec/x86_64/platform.cc
@@ -18,6 +18,7 @@
 #include <platform.h>
 #include <multiboot.h>
 #include <multiboot2.h>
+#include <port_io.h>

 #include <hw/memory_consts.h>
 #include <hw/spec/x86_64/acpi.h>
@@ -91,6 +92,58 @@ static uint32_t calibrate_tsc_frequency(addr_t fadt_addr)
 }


+static void calibrate_lapic_frequency(addr_t fadt_addr, uint32_t &ticks_per_ms, uint32_t &div)
+{
+	uint32_t const default_ticks_per_ms = TIMER_MIN_TICKS_PER_MS;
+	uint32_t const sleep_ms = 10;
+
+	if (!fadt_addr) {
+		warning("FADT not found, setting minimum Local APIC frequency of ", default_ticks_per_ms, "kHz");
+		ticks_per_ms = default_ticks_per_ms;
+	}
+
+	Hw::Acpi_fadt fadt(reinterpret_cast<Hw::Acpi_generic *>(fadt_addr));
+
+
+	Hw::Local_apic lapic(Hw::Cpu_memory_map::lapic_phys_base());
+
+	ticks_per_ms = 0;
+
+	lapic.calibrate_divider(ticks_per_ms, div, [&]() {
+			return fadt.calibrate_freq_khz(sleep_ms, [&]() {
+				return lapic.read<Hw::Local_apic::Tmr_current>();;
+		}, true);
+	});
+
+	if (!ticks_per_ms) {
+		warning("FADT not found, setting minimum Local APIC frequency of ", default_ticks_per_ms, "kHz");
+		ticks_per_ms = default_ticks_per_ms;
+	}
+}
+
+
+static void disable_pit()
+{
+	using Hw::outb;
+
+	enum {
+		/* PIT constants */
+		PIT_CH0_DATA   = 0x40,
+		PIT_MODE       = 0x43,
+	};
+
+	struct Calibration_failed : Genode::Exception { };
+
+	/**
+	 * Disable PIT timer channel. This is necessary since BIOS sets up
+	 * channel 0 to fire periodically.
+	 */
+	outb(PIT_MODE, 0x30);
+	outb(PIT_CH0_DATA, 0);
+	outb(PIT_CH0_DATA, 0);
+}
+
+
 Bootstrap::Platform::Board::Board()
 :
 	core_mmio(Memory_region { 0, 0x1000 },
@@ -275,8 +328,11 @@ Bootstrap::Platform::Board::Board()
 		cpus = !cpus ? 1 : max_cpus;
 	}

+	calibrate_lapic_frequency(info.acpi_fadt, info.lapic_ticks_per_ms, info.lapic_div);
 	info.tsc_freq_khz = calibrate_tsc_frequency(info.acpi_fadt);

+	disable_pit();
+
 	/* copy 16 bit boot code for AP CPUs and for ACPI resume */
 	addr_t ap_code_size = (addr_t)&_start - (addr_t)&_ap;
 	memcpy((void *)AP_BOOT_CODE_PAGE, &_ap, ap_code_size);
--- a/repos/base-hw/src/core/board/pc/board.h
+++ b/repos/base-hw/src/core/board/pc/board.h
@@ -21,7 +21,7 @@

 /* base-hw core includes */
 #include <spec/x86_64/pic.h>
-#include <spec/x86_64/pit.h>
+#include <spec/x86_64/timer.h>
 #include <spec/x86_64/cpu.h>

 namespace Board {
--- a/repos/base-hw/src/core/spec/x86_64/pic.cc
+++ b/repos/base-hw/src/core/spec/x86_64/pic.cc
@@ -47,6 +47,8 @@ Local_interrupt_controller(Global_interrupt_controller &global_irq_ctrl)

 void Local_interrupt_controller::init()
 {
+	using Hw::outb;
+
 	/* Start initialization sequence in cascade mode */
 	outb(PIC_CMD_MASTER, 0x11);
 	outb(PIC_CMD_SLAVE, 0x11);
--- a/repos/base-hw/src/core/spec/x86_64/pit.h
+++ b/repos/base-hw/src/core/spec/x86_64/pit.h
@@ -1,80 +0,0 @@
-/*
- * \brief  Timer driver for core
- * \author Adrian-Ken Rueegsegger
- * \author Reto Buerki
- * \date   2015-02-06
- */
-
-/*
- * Copyright (C) 2015-2017 Genode Labs GmbH
- *
- * This file is part of the Genode OS framework, which is distributed
- * under the terms of the GNU Affero General Public License version 3.
- */
-
-#ifndef _SRC__CORE__SPEC__ARM__PIT_H_
-#define _SRC__CORE__SPEC__ARM__PIT_H_
-
-/* Genode includes */
-#include <util/mmio.h>
-#include <base/stdint.h>
-
-/* core includes */
-#include <port_io.h>
-
-namespace Board { class Timer; }
-
-
-/**
- * LAPIC-based timer driver for core
- */
-struct Board::Timer: Genode::Mmio<Hw::Cpu_memory_map::LAPIC_SIZE>
-{
-	enum {
-		/* PIT constants */
-		PIT_TICK_RATE  = 1193182ul,
-		PIT_SLEEP_MS   = 50,
-		PIT_SLEEP_TICS = (PIT_TICK_RATE / 1000) * PIT_SLEEP_MS,
-		PIT_CH0_DATA   = 0x40,
-		PIT_CH2_DATA   = 0x42,
-		PIT_CH2_GATE   = 0x61,
-		PIT_MODE       = 0x43,
-	};
-
-	/* Timer registers */
-	struct Tmr_lvt : Register<0x320, 32>
-	{
-		struct Vector     : Bitfield<0,  8> { };
-		struct Delivery   : Bitfield<8,  3> { };
-		struct Mask       : Bitfield<16, 1> { };
-		struct Timer_mode : Bitfield<17, 2> { };
-	};
-
-	struct Tmr_initial : Register <0x380, 32> { };
-	struct Tmr_current : Register <0x390, 32> { };
-
-	struct Divide_configuration : Register <0x03e0, 32>
-	{
-		struct Divide_value_0_2 : Bitfield<0, 2> { };
-		struct Divide_value_2_1 : Bitfield<3, 1> { };
-		struct Divide_value :
-			Genode::Bitset_2<Divide_value_0_2, Divide_value_2_1>
-		{
-			enum { MAX = 6 };
-		};
-	};
-
-	struct Calibration_failed : Genode::Exception { };
-
-	Divide_configuration::access_t divider      = 0;
-	Genode::uint32_t               ticks_per_ms = 0;
-
-	/* Measure LAPIC timer frequency using PIT channel 2 */
-	Genode::uint32_t pit_calc_timer_freq(void);
-
-	Timer(unsigned);
-
-	void init();
-};
-
-#endif /* _SRC__CORE__SPEC__ARM__PIT_H_ */
--- a/repos/base-hw/src/core/spec/x86_64/timer.cc
+++ b/repos/base-hw/src/core/spec/x86_64/timer.cc
@@ -15,9 +15,6 @@

 #include <hw/spec/x86_64/x86_64.h>

-/* Genode includes */
-#include <drivers/timer/util.h>
-
 /* core includes */
 #include <kernel/timer.h>
 #include <platform.h>
@@ -25,37 +22,9 @@
 using namespace Core;
 using namespace Kernel;

-
-uint32_t Board::Timer::pit_calc_timer_freq(void)
-{
-	uint32_t t_start, t_end;
-
-	/* set channel gate high and disable speaker */
-	outb(PIT_CH2_GATE, (uint8_t)((inb(0x61) & ~0x02) | 0x01));
-
-	/* set timer counter (mode 0, binary count) */
-	outb(PIT_MODE, 0xb0);
-	outb(PIT_CH2_DATA, PIT_SLEEP_TICS & 0xff);
-	outb(PIT_CH2_DATA, PIT_SLEEP_TICS >> 8);
-
-	write<Tmr_initial>(~0U);
-
-	t_start = read<Tmr_current>();
-	while ((inb(PIT_CH2_GATE) & 0x20) == 0)
-	{
-		asm volatile("pause" : : : "memory");
-	}
-	t_end = read<Tmr_current>();
-
-	write<Tmr_initial>(0);
-
-	return (t_start - t_end) / PIT_SLEEP_MS;
-}
-
-
 Board::Timer::Timer(unsigned)
 :
-	Mmio({(char *)Platform::mmio_to_virt(Hw::Cpu_memory_map::lapic_phys_base()), Mmio::SIZE})
+	Local_apic(Platform::mmio_to_virt(Hw::Cpu_memory_map::lapic_phys_base()))
 {
 	init();
 }
@@ -75,28 +44,10 @@ void Board::Timer::init()
 		return;
 	}

-	/* calibrate LAPIC frequency to fullfill our requirements */
-	for (Divide_configuration::access_t div = Divide_configuration::Divide_value::MAX;
-	     div && ticks_per_ms < TIMER_MIN_TICKS_PER_MS; div--)
-	{
-		if (!div){
-			raw("Failed to calibrate timer frequency");
-			throw Calibration_failed();
-		}
-		write<Divide_configuration::Divide_value>((uint8_t)div);
-
-		/* Calculate timer frequency */
-		ticks_per_ms = pit_calc_timer_freq();
-		divider      = div;
-	}
-
-	/**
-	 * Disable PIT timer channel. This is necessary since BIOS sets up
-	 * channel 0 to fire periodically.
-	 */
-	outb(Board::Timer::PIT_MODE, 0x30);
-	outb(Board::Timer::PIT_CH0_DATA, 0);
-	outb(Board::Timer::PIT_CH0_DATA, 0);
+	Platform::apply_with_boot_info([&](auto const &boot_info) {
+			ticks_per_ms = boot_info.plat_info.lapic_ticks_per_ms;
+			divider = boot_info.plat_info.lapic_div;
+		});
 }


--- a/repos/base-hw/src/core/spec/x86_64/timer.h
+++ b/repos/base-hw/src/core/spec/x86_64/timer.h
@@ -0,0 +1,40 @@
+/*
+ * \brief  Timer driver for core
+ * \author Adrian-Ken Rueegsegger
+ * \author Reto Buerki
+ * \date   2015-02-06
+ */
+
+/*
+ * Copyright (C) 2015-2017 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU Affero General Public License version 3.
+ */
+
+#ifndef _SRC__CORE__SPEC__ARM__PIT_H_
+#define _SRC__CORE__SPEC__ARM__PIT_H_
+
+/* Genode includes */
+#include <base/stdint.h>
+
+/* hw includes */
+#include <hw/spec/x86_64/apic.h>
+
+namespace Board { class Timer; }
+
+
+/**
+ * LAPIC-based timer driver for core
+ */
+struct Board::Timer: public Hw::Local_apic
+{
+	Divide_configuration::access_t divider      = 0;
+	Genode::uint32_t               ticks_per_ms = 0;
+
+	Timer(unsigned);
+
+	void init();
+};
+
+#endif /* _SRC__CORE__SPEC__ARM__PIT_H_ */
--- a/repos/base-hw/src/include/hw/spec/x86_64/acpi.h
+++ b/repos/base-hw/src/include/hw/spec/x86_64/acpi.h
@@ -264,7 +264,7 @@ struct Hw::Acpi_fadt : Genode::Mmio<276>
 		return 0;
 	}

-	uint32_t calibrate_freq_khz(uint32_t sleep_ms, auto get_value_fn)
+	uint32_t calibrate_freq_khz(uint32_t sleep_ms, auto get_value_fn, bool reverse = false)
 	{
 		unsigned const acpi_timer_freq = 3'579'545;

@@ -277,7 +277,7 @@ struct Hw::Acpi_fadt : Genode::Mmio<276>
 			asm volatile ("pause":::"memory");
 		uint64_t const t2 = get_value_fn();

-		return (uint32_t)((t2 - t1) / sleep_ms);
+		return (uint32_t)((reverse ? (t1 - t2) : (t2 - t1)) / sleep_ms);
 	}

 	void write_cnt_blk(unsigned value_a, unsigned value_b)
--- a/repos/base-hw/src/include/hw/spec/x86_64/apic.h
+++ b/repos/base-hw/src/include/hw/spec/x86_64/apic.h
@@ -18,6 +18,9 @@ namespace Hw { class Local_apic; }

 #include <hw/spec/x86_64/x86_64.h>

+/* Genode includes */
+#include <drivers/timer/util.h>
+
 struct Hw::Local_apic : Genode::Mmio<Hw::Cpu_memory_map::LAPIC_SIZE>
 {
 	struct Id  : Register<0x020, 32> { };
@@ -58,6 +61,52 @@ struct Hw::Local_apic : Genode::Mmio<Hw::Cpu_memory_map::LAPIC_SIZE>
 		struct Destination : Bitfield<24, 8> { };
 	};

+	/* Timer registers */
+	struct Tmr_lvt : Register<0x320, 32>
+	{
+		struct Vector     : Bitfield<0,  8> { };
+		struct Delivery   : Bitfield<8,  3> { };
+		struct Mask       : Bitfield<16, 1> { };
+		struct Timer_mode : Bitfield<17, 2> { };
+	};
+
+	struct Tmr_initial : Register <0x380, 32> { };
+	struct Tmr_current : Register <0x390, 32> { };
+
+	struct Divide_configuration : Register <0x03e0, 32>
+	{
+		struct Divide_value_0_2 : Bitfield<0, 2> { };
+		struct Divide_value_2_1 : Bitfield<3, 1> { };
+		struct Divide_value :
+			Genode::Bitset_2<Divide_value_0_2, Divide_value_2_1>
+		{
+			enum { MAX = 6 };
+		};
+	};
+
+	void calibrate_divider(uint32_t &ticks_per_ms, uint32_t &divider, auto calibration_fn)
+	{
+		/* calibrate LAPIC frequency to fullfill our requirements */
+		for (Divide_configuration::access_t div = Divide_configuration::Divide_value::MAX;
+		     div && ticks_per_ms < TIMER_MIN_TICKS_PER_MS; div--)
+		{
+			if (!div) {
+				raw("Failed to calibrate Local APIC frequency");
+				ticks_per_ms = 0;
+				break;
+			}
+			write<Divide_configuration::Divide_value>((uint8_t)div);
+
+			write<Tmr_initial>(~0U);
+
+			/* Calculate timer frequency */
+			ticks_per_ms = calibration_fn();
+			divider      = div;
+
+			write<Tmr_initial>(0);
+		}
+	}
+
 	Local_apic(addr_t const addr) : Mmio({(char*)addr, Mmio::SIZE}) {}
 };

--- a/repos/base-hw/src/include/hw/spec/x86_64/pc_board.h
+++ b/repos/base-hw/src/include/hw/spec/x86_64/pc_board.h
@@ -45,6 +45,8 @@ struct Hw::Pc_board::Boot_info
 	Genode::addr_t   efi_system_table { 0 };
 	Genode::addr_t   acpi_fadt        { 0 };
 	Genode::uint32_t tsc_freq_khz     { 0 };
+	Genode::uint32_t lapic_ticks_per_ms { 0 };
+	Genode::uint32_t lapic_div          { 0 };

 	Boot_info() {}
 	Boot_info(Acpi_rsdp    const &acpi_rsdp,
--- a/repos/dde_bsd/recipes/pkg/bsd_audio/hash
+++ b/repos/dde_bsd/recipes/pkg/bsd_audio/hash
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