Map Multiprocessor Specification (MP) configuration table (#113)

Map the MP table so we can use it as a fallback for the ACPI MADT on
older systems.

include/kernel/infrastructure/acpi/acpi.h

@@ -38,6 +38,8 @@
 #include <stdbool.h>
 #include <stddef.h>
 
+bool verify_acpi_checksum(const void *buffer, size_t buflen);
+
 bool verify_acpi_rsdp(const acpi_rsdp_t *rsdp);
 
 void map_acpi_tables(kern_paddr_t rsdp_paddr, const acpi_table_def_t *table_defs);

include/kernel/infrastructure/acpi/tables.h

@@ -150,7 +150,7 @@ typedef PACKED_STRUCT {
     acpi_table_header_t header;
     uint32_t            local_intr_controller_addr;
     uint32_t            flags;
-    char                entries[];
+    const char          entries[];
 } acpi_madt_t;
 
 typedef PACKED_STRUCT {

include/kernel/infrastructure/i686/firmware/asm/bios.h

@@ -34,4 +34,6 @@
 
 #define BIOS_BDA_EBDA_SEGMENT   0x40e
 
+#define BIOS_BDA_MEMORY_SIZE    0x413
+
 #endif

include/kernel/infrastructure/i686/firmware/asm/mp.h

@@ -0,0 +1,125 @@
+/*
+ * Copyright (C) 2025 Philippe Aubertin.
+ * All rights reserved.
+
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 
+ * 3. Neither the name of the author nor the names of other contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef JINUE_KERNEL_INFRASTRUCTURE_I686_FIRMWARE_ASM_MP_H
+#define JINUE_KERNEL_INFRASTRUCTURE_I686_FIRMWARE_ASM_MP_H
+
+/* Multiprocessor Specification 1.4 section 4.1 MP Floating Pointer
+ * Structure */
+
+#define MP_FLOATING_PTR_SIGNATURE   "_MP_"
+
+
+/* Table 4-1. MP Floating Pointer Structure Fields, flags in the MP Feature
+ * Information byte 2 field. Bit 6 is defined in Appendix E Errata. */
+
+#define MP_FEATURE2_IMCRP                   (1 << 7)
+
+#define MP_FEATURE2_MULTIPLE_CLK_SOURCES    (1 << 6)
+
+/* Multiprocessor Specification 1.4 section 4.2 MP Configuration Table
+ * Header */
+
+#define MP_CONF_TABLE_SIGNATURE     "PCMP"
+
+#define MP_REVISION_V1_1            1
+
+#define MP_REVISION_V1_4            4
+
+/* Multiprocessor Specification 1.4 Table 4-3 Base MP Configuration Table Entry
+ * Types */
+
+#define MP_ENTRY_TYPE_PROCESSOR     0
+
+#define MP_ENTRY_TYPE_BUS           1
+
+#define MP_ENTRY_TYPE_IO_APIC       2
+
+#define MP_ENTRY_TYPE_IO_INTR       3
+
+#define MP_ENTRY_TYPE_LOCAL_INTR    4
+
+/* Multiprocessor Specification 1.4 Table 4-8 Bus Type String Values */
+
+#define MP_BUS_TYPE_EISA            "EISA"
+
+#define MP_BUS_TYPE_ISA             "ISA"
+
+#define MP_BUS_TYPE_PCI             "PCI"
+
+/* Multiprocessor Specification 1.4 section 4.3.3 I/O APIC Entries */
+
+#define MP_IO_API_FLAG_EN           (1 << 0)
+
+/* Multiprocessor Specification 1.4 Table 4-10 I/O Interrupt Entry Fields */
+
+#define MP_PO_BUS_DEFAULT           0
+
+#define MP_PO_ACTIVE_HIGH           1
+
+#define MP_PO_ACTIVE_LOW            3
+
+
+#define MP_EL_BUS_DEFAULT           (0 << 2)
+
+#define MP_EL_EDGE                  (1 << 2)
+
+#define MP_EL_LEVEL                 (2 << 2)
+
+/* Multiprocessor Specification 1.4 Table 4-11 Interrupt Type Values */
+
+#define MP_INTR_TYPE_INT            0
+
+#define MP_INTR_TYPE_NMI            1
+
+#define MP_INTR_TYPE_SMI            2
+
+#define MP_INTR_TYPE_EXTINT         3
+
+/* Multiprocessor Specification 1.4 Table 5-1 Default Configurations */
+
+#define MP_NO_DEFAULT               0
+
+#define MP_DEFAULT_ISA              1
+
+#define MP_DEFAULT_EISA_NO_IRQ0     2
+
+#define MP_DEFAULT_EISA             3
+
+#define MP_DEFAULT_MCA              4
+
+#define MP_DEFAULT_ISA_PCI_APIC     5
+
+#define MP_DEFAULT_EISA_PIC_APIC    6
+
+#define MP_DEFAULT_MCA_PCI_APIC     7
+
+#endif

include/kernel/infrastructure/i686/firmware/bios.h

@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2025 Philippe Aubertin.
+ * All rights reserved.
+
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 
+ * 3. Neither the name of the author nor the names of other contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef JINUE_KERNEL_INFRASTRUCTURE_I686_FIRMWARE_BIOS_H
+#define JINUE_KERNEL_INFRASTRUCTURE_I686_FIRMWARE_BIOS_H
+
+#include <kernel/infrastructure/i686/firmware/asm/bios.h>
+#include <stddef.h>
+#include <stdint.h>
+
+uint32_t get_bios_ebda_addr(void);
+
+size_t get_bios_base_memory_size(void);
+
+#endif

include/kernel/infrastructure/i686/firmware/mp.h

@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2025 Philippe Aubertin.
+ * All rights reserved.
+
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 
+ * 3. Neither the name of the author nor the names of other contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef JINUE_KERNEL_INFRASTRUCTURE_I686_FIRMWARE_MP_H
+#define JINUE_KERNEL_INFRASTRUCTURE_I686_FIRMWARE_MP_H
+
+#include <kernel/infrastructure/i686/firmware/asm/mp.h>
+#include <stdint.h>
+
+/* Multiprocessor Specification 1.4 section 4.1 MP Floating Pointer
+ * Structure */
+
+typedef struct {
+    char        signature[4];
+    uint32_t    addr;
+    uint8_t     length;
+    uint8_t     revision;
+    uint8_t     checksum;
+    uint8_t     feature1;
+    uint8_t     feature2;
+    uint8_t     feature_reserved[3];
+} mp_ptr_struct_t;
+
+/* Multiprocessor Specification 1.4 section 4.2 MP Configuration Table
+ * Header */
+
+typedef struct {
+    char        signature[4];
+    uint16_t    base_length;
+    uint8_t     revision;
+    uint8_t     checksum;
+    char        oem_id[8];
+    char        product_id[12];
+    uint32_t    oem_table_addr;
+    uint16_t    oem_table_size;
+    uint16_t    entry_count;
+    uint32_t    lapic_addr;
+    uint16_t    ext_table_length;
+    uint8_t     ext_table_checksum;
+    uint8_t     reserved;
+    const char  entries[];
+} mp_conf_table_t;
+
+/* Multiprocessor Specification 1.4 section 4.3.1 Processor Entries */
+
+typedef struct {
+    uint8_t     entry_type;
+    uint8_t     apic_id;
+    uint8_t     apic_version;
+    uint8_t     cpu_flags;
+    uint32_t    cpu_signature;
+    uint32_t    feature_flags;
+    uint32_t    reserved1;
+    uint32_t    reserved2;
+} mp_entry_processor_t;
+
+/* Multiprocessor Specification 1.4 section 4.3.2 Bus Entries */
+
+typedef struct {
+    uint8_t     entry_type;
+    uint8_t     bus_id;
+    char        bus_type[6];
+} mp_entry_bus_t;
+
+/* Multiprocessor Specification 1.4 section 4.3.3 I/O APIC Entries */
+
+typedef struct {
+    uint8_t     entry_type;
+    uint8_t     apic_id;
+    uint8_t     apic_version;
+    uint8_t     flag;
+    uint32_t    addr;
+} mp_entry_ioapic_t;
+
+/* Multiprocessor Specification 1.4 section 4.3.4 I/O Interrupt Assignment
+ * Entries and 4.3.5 Local Interrupt Assignment Entries */
+
+typedef struct {
+    uint8_t     entry_type;
+    uint8_t     intr_type;
+    uint16_t    io_intr_flag;
+    uint8_t     source_bus_id;
+    uint8_t     source_bus_irq;
+    uint8_t     dest_apic_id;
+    uint8_t     dest_apic_intn;
+} mp_entry_intr_t;
+
+void find_mp(void);
+
+void init_mp(void);
+
+#endif

kernel/Makefile

@@ -107,6 +107,8 @@ sources.kernel.c = \
 	infrastructure/i686/drivers/uart16550a.c \
 	infrastructure/i686/drivers/vga.c \
 	infrastructure/i686/firmware/acpi.c \
+	infrastructure/i686/firmware/bios.c \
+	infrastructure/i686/firmware/mp.c \
 	infrastructure/i686/pmap/nopae.c \
 	infrastructure/i686/pmap/pmap.c \
 	infrastructure/i686/pmap/pae.c \

kernel/infrastructure/acpi/acpi.c

@@ -37,13 +37,17 @@
 #include <string.h>
 
 /**
- * Verify the checksum of an ACPI data structure
+ * Verify the checksum of an ACPI data structure (RSDP, RSDT, ACPI table)
+ * 
+ * On x86, this function is also used to verify the checksum of the floating
+ * pointer structure and MP configuration table header from Intel's
+ * Multiprocessor Specification since the checksum algorithm is the same.
  *
- * @param buffer pointer to ACPI data structure
+ * @param buffer pointer to ACPI (or MP) data structure
  * @param buflen size of ACPI data structure
  * @return true for correct checksum, false for checksum mismatch
  */
-static bool verify_checksum(const void *buffer, size_t buflen) {
+bool verify_acpi_checksum(const void *buffer, size_t buflen) {
     uint8_t sum = 0;
 
     for(int idx = 0; idx < buflen; ++idx) {
@@ -64,7 +68,7 @@ bool verify_acpi_rsdp(const acpi_rsdp_t *rsdp) {
         return false;
     }
 
-    if(!verify_checksum(rsdp, ACPI_V1_RSDP_SIZE)) {
+    if(!verify_acpi_checksum(rsdp, ACPI_V1_RSDP_SIZE)) {
         return false;
     }
 
@@ -76,7 +80,7 @@ bool verify_acpi_rsdp(const acpi_rsdp_t *rsdp) {
         return false;
     }
 
-    return verify_checksum(rsdp, sizeof(acpi_rsdp_t));
+    return verify_acpi_checksum(rsdp, sizeof(acpi_rsdp_t));
 }
 
 /**
@@ -123,7 +127,7 @@ static const void *map_table(const acpi_table_header_t *header) {
 
     resize_map_in_kernel(header->length);
 
-    if(! verify_checksum(header, header->length)) {
+    if(! verify_acpi_checksum(header, header->length)) {
         return NULL;
     }