summaryrefslogtreecommitdiff
path: root/boot
diff options
context:
space:
mode:
authorFreya Murphy <freya@freyacat.org>2025-04-03 12:30:15 -0400
committerFreya Murphy <freya@freyacat.org>2025-04-03 12:30:15 -0400
commit4d0603e8e5de4bb076d029ecb03d0e2c35fd69fa (patch)
tree9cdde04b52f69ae2169fdeb2dc5dc5a9a63773f6 /boot
parentrefactor include (diff)
downloadcomus-4d0603e8e5de4bb076d029ecb03d0e2c35fd69fa.tar.gz
comus-4d0603e8e5de4bb076d029ecb03d0e2c35fd69fa.tar.bz2
comus-4d0603e8e5de4bb076d029ecb03d0e2c35fd69fa.zip
move boot only headers to boot
Diffstat (limited to 'boot')
-rw-r--r--boot/boot.S4
-rw-r--r--boot/include/arch.h303
-rw-r--r--boot/include/bios.h73
-rw-r--r--boot/include/bootstrap.h117
4 files changed, 495 insertions, 2 deletions
diff --git a/boot/boot.S b/boot/boot.S
index 7882672..b16239a 100644
--- a/boot/boot.S
+++ b/boot/boot.S
@@ -30,8 +30,8 @@
#define ASM_SRC
#include <bootstrap.h>
-#include <x86/bios.h>
-#include <x86/arch.h>
+#include <bios.h>
+#include <arch.h>
/*
** Symbol for locating the beginning of the code.
diff --git a/boot/include/arch.h b/boot/include/arch.h
new file mode 100644
index 0000000..113c76b
--- /dev/null
+++ b/boot/include/arch.h
@@ -0,0 +1,303 @@
+/*
+** @file arch.h
+**
+** @author Warren R. Carithers
+** @author K. Reek
+**
+** Definitions of constants and macros for use
+** with the x86 architecture and registers.
+**
+*/
+
+#ifndef X86ARCH_H_
+#define X86ARCH_H_
+
+/*
+** Video stuff
+*/
+#define VID_BASE_ADDR 0xB8000
+
+/*
+** Memory management
+*/
+#define SEG_PRESENT 0x80
+#define SEG_PL_0 0x00
+#define SEG_PL_1 0x20
+#define SEG_PL_2 0x40
+#define SEG_PL_3 0x50
+#define SEG_SYSTEM 0x00
+#define SEG_NON_SYSTEM 0x10
+#define SEG_32BIT 0x04
+#define DESC_IGATE 0x06
+
+/*
+** Exceptions
+*/
+#define N_EXCEPTIONS 256
+
+/*
+** Bit definitions in registers
+**
+** See IA-32 Intel Architecture SW Dev. Manual, Volume 3: System
+** Programming Guide, page 2-8.
+*/
+
+/*
+** EFLAGS
+*/
+#define EFL_RSVD 0xffc00000 /* reserved */
+#define EFL_MB0 0x00008020 /* must be zero */
+#define EFL_MB1 0x00000002 /* must be 1 */
+
+#define EFL_ID 0x00200000
+#define EFL_VIP 0x00100000
+#define EFL_VIF 0x00080000
+#define EFL_AC 0x00040000
+#define EFL_VM 0x00020000
+#define EFL_RF 0x00010000
+#define EFL_NT 0x00004000
+#define EFL_IOPL 0x00003000
+#define EFL_OF 0x00000800
+#define EFL_DF 0x00000400
+#define EFL_IF 0x00000200
+#define EFL_TF 0x00000100
+#define EFL_SF 0x00000080
+#define EFL_ZF 0x00000040
+#define EFL_AF 0x00000010
+#define EFL_PF 0x00000004
+#define EFL_CF 0x00000001
+
+/*
+** CR0, CR1, CR2, CR3, CR4
+**
+** IA-32 V3, page 2-12.
+*/
+#define CR0_RSVD 0x1ffaffc0
+#define CR0_PG 0x80000000
+#define CR0_CD 0x40000000
+#define CR0_NW 0x20000000
+#define CR0_AM 0x00040000
+#define CR0_WP 0x00010000
+#define CR0_NE 0x00000020
+#define CR0_ET 0x00000010
+#define CR0_TS 0x00000008
+#define CR0_EM 0x00000004
+#define CR0_MP 0x00000002
+#define CR0_PE 0x00000001
+
+#define CR1_RSVD 0xffffffff
+
+#define CR2_RSVD 0x00000000
+#define CR2_PF_LIN_ADDR 0xffffffff
+
+#define CR3_RSVD 0x00000fe7
+#define CR3_PD_BASE 0xfffff000
+#define CR3_PCD 0x00000010
+#define CR3_PWT 0x00000008
+
+#define CR4_RSVD 0xfd001000
+#define CR4_UINT 0x02000000
+#define CR4_PKS 0x01000000
+#define CR4_CET 0x00800000
+#define CR4_PKE 0x00400000
+#define CR4_SMAP 0x00200000
+#define CR4_SMEP 0x00100000
+#define CR4_KL 0x00080000
+#define CR4_OSXS 0x00040000
+#define CR4_PCID 0x00020000
+#define CR4_FSGS 0x00010000
+#define CR4_SMXE 0x00004000
+#define CR4_VMXE 0x00002000
+#define CR4_LA57 0x00001000
+#define CR4_UMIP 0x00000800
+#define CR4_OSXMMEXCPT 0x00000400
+#define CR4_OSFXSR 0x00000200
+#define CR4_PCE 0x00000100
+#define CR4_PGE 0x00000080
+#define CR4_MCE 0x00000040
+#define CR4_PAE 0x00000020
+#define CR4_PSE 0x00000010
+#define CR4_DE 0x00000008
+#define CR4_TSD 0x00000004
+#define CR4_PVI 0x00000002
+#define CR4_VME 0x00000001
+
+/*
+** PMode segment selector field masks
+**
+** IA-32 V3, page 3-8.
+*/
+#define SEG_SEL_IX_MASK 0xfff8
+#define SEG_SEL_TI_MASK 0x0004
+#define SEG_SEL_RPL_MASK 0x0003
+
+/*
+** Segment descriptor bytes
+**
+** IA-32 V3, page 3-10.
+**
+** Bytes:
+** 0, 1: segment limit 15:0
+** 2, 3: base address 15:0
+** 4: base address 23:16
+** 7: base address 31:24
+*/
+
+/*
+** Byte 5: access control bits
+** 7: present
+** 6-5: DPL
+** 4: system/user
+** 3-0: type
+*/
+#define SEG_ACCESS_P_MASK 0x80
+# define SEG_PRESENT 0x80
+# define SEG_NOT_PRESENT 0x00
+
+#define SEG_ACCESS_DPL_MASK 0x60
+# define SEG_DPL_0 0x00
+# define SEG_DPL_1 0x20
+# define SEG_DPL_2 0x40
+# define SEG_DPL_3 0x60
+
+#define SEG_ACCESS_S_MASK 0x10
+# define SEG_SYSTEM 0x00
+# define SEG_NON_SYSTEM 0x10
+
+#define SEG_TYPE_MASK 0x0f
+# define SEG_DATA_A_BIT 0x1
+# define SEG_DATA_W_BIT 0x2
+# define SEG_DATA_E_BIT 0x4
+# define SEG_CODE_A_BIT 0x1
+# define SEG_CODE_R_BIT 0x2
+# define SEG_CODE_C_BIT 0x4
+# define SEG_DATA_RO 0x0
+# define SEG_DATA_ROA 0x1
+# define SEG_DATA_RW 0x2
+# define SEG_DATA_RWA 0x3
+# define SEG_DATA_RO_XD 0x4
+# define SEG_DATA_RO_XDA 0x5
+# define SEG_DATA_RW_XW 0x6
+# define SEG_DATA_RW_XWA 0x7
+# define SEG_CODE_XO 0x8
+# define SEG_CODE_XOA 0x9
+# define SEG_CODE_XR 0xa
+# define SEG_CODE_XRA 0xb
+# define SEG_CODE_XO_C 0xc
+# define SEG_CODE_XO_CA 0xd
+# define SEG_CODE_XR_C 0xe
+# define SEG_CODE_XR_CA 0xf
+
+/*
+** Byte 6: sizes
+** 7: granularity
+** 6: d/b
+** 5: long mode
+** 4: available!
+** 3-0: upper 4 bits of limit
+** 7: base address 31:24
+*/
+#define SEG_SIZE_G_MASK 0x80
+# define SEG_GRAN_BYTE 0x00
+# define SEG_GRAN_4KBYTE 0x80
+
+#define SEG_SIZE_D_B_MASK 0x40
+# define SEG_DB_16BIT 0x00
+# define SEG_DB_32BIT 0x40
+
+#define SEG_SIZE_L_MASK 0x20
+# define SEG_L_64BIT 0x20
+# define SEG_L_32BIT 0x00
+
+#define SEG_SIZE_AVL_MASK 0x10
+
+#define SEG_SIZE_LIM_19_16_MASK 0x0f
+
+
+/*
+** System-segment and gate-descriptor types
+**
+** IA-32 V3, page 3-15.
+*/
+ // type 0: reserved
+#define SEG_SYS_16BIT_TSS_AVAIL 0x1
+#define SEG_SYS_LDT 0x2
+#define SEG_SYS_16BIT_TSS_BUSY 0x3
+#define SEG_SYS_16BIT_CALL_GATE 0x4
+#define SEG_SYS_TASK_GATE 0x5
+#define SEG_SYS_16BIT_INT_GATE 0x6
+#define SEG_SYS_16BIT_TRAP_GATE 0x7
+ // type 8: reserved
+#define SEG_SYS_32BIT_TSS_AVAIL 0x9
+ // type A: reserved
+#define SEG_SYS_32BIT_TSS_BUSY 0xb
+#define SEG_SYS_32BIT_CALL_GATE 0xc
+ // type D: reserved
+#define SEG_SYS_32BIT_INT_GATE 0xe
+#define SEG_SYS_32BIT_TRAP_GATE 0xf
+
+/*
+** IDT Descriptors
+**
+** IA-32 V3, page 5-13.
+**
+** All have a segment selector in bytes 2 and 3; Task Gate descriptors
+** have bytes 0, 1, 4, 6, and 7 reserved; others have bytes 0, 1, 6,
+** and 7 devoted to the 16 bits of the Offset, with the low nybble of
+** byte 4 reserved.
+*/
+#define IDT_PRESENT 0x8000
+#define IDT_DPL_MASK 0x6000
+# define IDT_DPL_0 0x0000
+# define IDT_DPL_1 0x2000
+# define IDT_DPL_2 0x4000
+# define IDT_DPL_3 0x6000
+#define IDT_GATE_TYPE 0x0f00
+# define IDT_TASK_GATE 0x0500
+# define IDT_INT16_GATE 0x0600
+# define IDT_INT32_GATE 0x0e00
+# define IDT_TRAP16_GATE 0x0700
+# define IDT_TRAP32_GATE 0x0f00
+
+/*
+** Interrupt vectors
+*/
+
+// predefined by the architecture
+#define VEC_DIVIDE_ERROR 0x00
+#define VEC_DEBUG_EXCEPTION 0x01
+#define VEC_NMI_INTERRUPT 0x02
+#define VEC_BREAKPOINT 0x03
+#define VEC_OVERFLOW 0x04
+#define VEC_BOUND_RANGE_EXCEEDED 0x05
+#define VEC_INVALID_OPCODE 0x06
+#define VEC_DEVICE_NOT_AVAILABLE 0x07
+#define VEC_DOUBLE_FAULT 0x08
+#define VEC_COPROCESSOR_OVERRUN 0x09
+#define VEC_INVALID_TSS 0x0a
+#define VEC_SEGMENT_NOT_PRESENT 0x0b
+#define VEC_STACK_FAULT 0x0c
+#define VEC_GENERAL_PROTECTION 0x0d
+#define VEC_PAGE_FAULT 0x0e
+// 0x0f is reserved - unused
+#define VEC_FPU_ERROR 0x10
+#define VEC_ALIGNMENT_CHECK 0x11
+#define VEC_MACHINE_CHECK 0x12
+#define VEC_SIMD_FP_EXCEPTION 0x13
+#define VEC_VIRT_EXCEPTION 0x14
+#define VEC_CTRL_PROT_EXCEPTION 0x15
+// 0x16 through 0x1f are reserved
+
+// 0x20 through 0xff are user-defined, non-reserved
+
+// IRQ0 through IRQ15 will use vectors 0x20 through 0x2f
+#define VEC_TIMER 0x20
+#define VEC_KBD 0x21
+#define VEC_COM2 0x23
+#define VEC_COM1 0x24
+#define VEC_PARALLEL 0x25
+#define VEC_FLOPPY 0x26
+#define VEC_MYSTERY 0x27
+#define VEC_MOUSE 0x2c
+
+#endif
diff --git a/boot/include/bios.h b/boot/include/bios.h
new file mode 100644
index 0000000..a19e570
--- /dev/null
+++ b/boot/include/bios.h
@@ -0,0 +1,73 @@
+/*
+** @file bios.h
+**
+** @author Warren R. Carithers
+**
+** BIOS-related declarations
+*/
+
+#ifndef BIOS_H_
+#define BIOS_H_
+
+/*
+** BIOS-related memory addresses
+*/
+
+#define BIOS_BDA 0x0400
+
+/*
+** Selected BIOS interrupt numbers
+*/
+
+#define BIOS_TIMER 0x08
+#define BIOS_KBD 0x09
+#define BIOS_VIDEO 0x10
+#define BIOS_EQUIP 0x11
+#define BIOS_MSIZ 0x12
+#define BIOS_DISK 0x13
+#define BIOS_SERIAL 0x14
+#define BIOS_MISC 0x15
+#define BIOS_KBDSVC 0x16
+#define BIOS_PRTSVC 0x17
+#define BIOS_BOOT 0x19
+#define BIOS_RTCPCI 0x1a
+
+// BIOS video commands (AH)
+#define BV_W_ADV 0x0e
+
+// BIOS disk commands (AH)
+#define BD_RESET 0x00
+#define BD_CHECK 0x01
+#define BD_RDSECT 0x02
+#define BD_WRSECT 0x03
+#define BD_PARAMS 0x08
+
+// BIOS disk commands with parameters (AX)
+#define BD_READ(n) ((BD_RDSECT << 8) | (n))
+#define BD_READ1 0x0201
+
+// CMOS ports (used for masking NMIs)
+#define CMOS_ADDR 0x70
+#define CMOS_DATA 0x71
+
+// important related commands
+#define NMI_ENABLE 0x00
+#define NMI_DISABLE 0x80
+
+/*
+** Physical Memory Map Table (0000:2D00 - 0000:7c00)
+**
+** Primarily used with the BIOS_MISC interrupt
+*/
+#define MMAP_SEG 0x02D0
+#define MMAP_DISP 0x0000
+#define MMAP_ADDR ((MMAP_SEG << 4) + MMAP_DISP)
+#define MMAP_SECTORS 0x0a
+
+#define MMAP_ENT 24 /* bytes per entry */
+#define MMAP_MAX_ENTS (BOOT_ADDR - MMAP_ADDR - 4) / 24
+
+#define MMAP_CODE 0xE820 /* int 0x15 code */
+#define MMAP_MAGIC_NUM 0x534D4150 /* for 0xE820 interrupt */
+
+#endif
diff --git a/boot/include/bootstrap.h b/boot/include/bootstrap.h
new file mode 100644
index 0000000..856d4eb
--- /dev/null
+++ b/boot/include/bootstrap.h
@@ -0,0 +1,117 @@
+/*
+** SCCS ID: @(#)bootstrap.h 2.4 1/22/25
+**
+** @file bootstrap.h
+**
+** @author K. Reek
+** @author Warren R. Carithers, Garrett C. Smith
+**
+** Addresses where various stuff goes in memory.
+*/
+
+#ifndef BOOTSTRAP_H_
+#define BOOTSTRAP_H_
+
+/*
+** The boot device
+*/
+#define BDEV_FLOPPY 0x00
+#define BDEV_USB 0x80 /* hard drive */
+
+#define BDEV BDEV_USB /* default */
+
+/*
+** Bootstrap definitions
+*/
+#define BOOT_SEG 0x07c0 /* 07c0:0000 */
+#define BOOT_DISP 0x0000
+#define BOOT_ADDR (BOOT_SEG << 4 + BOOT_DISP)
+
+#define PART2_DISP 0x0200 /* 07c0:0200 */
+#define PART2_ADDR (BOOT_SEG << 4 + PART2_DISP)
+
+#define SECTOR_SIZE 0x200 /* 512 bytes */
+
+/* Note: this assumes the bootstrap is two sectors long! */
+#define BOOT_SIZE (SECTOR_SIZE + SECTOR_SIZE)
+
+#define OFFSET_LIMIT (0x10000 - SECTOR_SIZE)
+
+#define BOOT_SP_DISP 0x4000 /* stack pointer 07c0:4000, or 0xbc00 */
+#define BOOT_SP_ADDR (BOOT_SEG << 4 + BOOT_SP_DISP)
+
+#define SECTOR1_END (BOOT_ADDR + SECTOR_SIZE)
+#define SECTOR2_END (BOOT_ADDR + BOOT_SIZE)
+
+
+/*
+** The target program itself
+*/
+#define TARGET_SEG 0x00001000 /* 1000:0000 */
+#define TARGET_ADDR 0x00010000 /* and upward */
+#define TARGET_STACK 0x00010000 /* and downward */
+
+/*
+** The Global Descriptor Table (0000:0500 - 0000:2500)
+*/
+#define GDT_SEG 0x00000050
+#define GDT_ADDR 0x00000500
+
+ /* segment register values */
+#define GDT_LINEAR 0x0008 /* All of memory, R/W */
+#define GDT_CODE 0x0010 /* All of memory, R/E */
+#define GDT_DATA 0x0018 /* All of memory, R/W */
+#define GDT_STACK 0x0020 /* All of memory, R/W */
+
+/*
+** The Interrupt Descriptor Table (0000:2500 - 0000:2D00)
+*/
+#define IDT_SEG 0x00000250
+#define IDT_ADDR 0x00002500
+
+/*
+** Additional I/O ports used by the bootstrap code
+*/
+
+// keyboard controller
+#define KBD_DATA 0x60
+#define KBD_CMD 0x64
+#define KBD_STAT 0x64
+
+// status register bits
+#define KBD_OBSTAT 0x01
+#define KBD_IBSTAT 0x02
+#define KBD_SYSFLAG 0x04
+#define KBD_CMDDAT 0x08
+
+// commands
+#define KBD_P1_DISABLE 0xad
+#define KBD_P1_ENABLE 0xae
+#define KBD_RD_OPORT 0xd0
+#define KBD_WT_OPORT 0xd1
+
+#ifdef ASM_SRC
+
+// segment descriptor macros for use in assembly source files
+// layout:
+// .word lower 16 bits of limit
+// .word lower 16 bits of base
+// .byte middle 8 bits of base
+// .byte type byte
+// .byte granularity byte
+// .byte upper 8 bits of base
+// we use 4K units, so we ignore the lower 12 bits of the limit
+#define SEGNULL \
+ .word 0, 0, 0, 0
+
+#define SEGMENT(base,limit,dpl,type) \
+ .word (((limit) >> 12) & 0xffff); \
+ .word ((base) & 0xffff) ; \
+ .byte (((base) >> 16) & 0xff) ; \
+ .byte (SEG_PRESENT | (dpl) | SEG_NON_SYSTEM | (type)) ; \
+ .byte (SEG_GRAN_4KBYTE | SEG_DB_32BIT | (((limit) >> 28) & 0xf)) ; \
+ .byte (((base) >> 24) & 0xff)
+
+#endif /* ASM_SRC */
+
+#endif