From 4836f3e5ca29ed5e2dacbe7e6e17a6e62333ac5f Mon Sep 17 00:00:00 2001 From: pjht Date: Fri, 24 Mar 2023 08:09:51 -0500 Subject: [PATCH] Change to a higher-half kernel --- Tuprules.tup | 2 +- boot/boot.68k | 14 ++- config.toml | 8 +- kernel/kernel.ld | 257 ++++++++--------------------------------------- kernel/main.68k | 4 +- kernel/start.68k | 92 +++++++++++++++++ 6 files changed, 148 insertions(+), 229 deletions(-) create mode 100644 kernel/start.68k diff --git a/Tuprules.tup b/Tuprules.tup index e40cba6..50a35f9 100644 --- a/Tuprules.tup +++ b/Tuprules.tup @@ -1,5 +1,5 @@ .gitignore -LDFLAGS = -z max-page-size=1 +LDFLAGS = -z max-page-size=4096 ASFLAGS = -m68010 --register-prefix-optional !as = |> m68k-elf-as $(ASFLAGS) -o %o %f |> %B.o diff --git a/boot/boot.68k b/boot/boot.68k index 4d46e65..2caaf27 100644 --- a/boot/boot.68k +++ b/boot/boot.68k @@ -14,7 +14,7 @@ bsr.w find_first_card move.l #PHDR_BUF_START, a1 | Set the destination address to PHDR_BUF_START move.l #0x2, d0 | Set the starting sector number to 2 move.l #PHDR_BUF_SEC_SIZE, d1 | Set the sector count -bsr.b read_sectors +bsr.w read_sectors move.l (PHDR_BUF_START + 0x1C), d0 | Load the offset of the program headers in the file move.l #PHDR_BUF_START, a1 | Put the address of the program headers in a1 adda.w d0, a1 @@ -27,25 +27,29 @@ bne.b next_seg | Zero the destination memory move.l (20, a1), d1 | Put the memory size - 1 in d1 subq.l #0x1, d1 -move.l (8, a1), a2 | Put the starting memory address in a2 +move.l (12, a1), a2 | Put the starting memory address in a2 zero_loop: move.b #0, (a2)+ | Zero a byte of the destination memory dbra d1, zero_loop | Loop back if there is more to zero | Load the segment data off disk move.l (16, a1), d1 | Put the file size in d1 beq.b next_seg | If the file size is 0, skip the copy (ex, .bss section) -move.l a1,a6 | Save a1 in a6 +move.l a1,a5 | Save a1 in a5 move.l d0,d4 | Save d0 in d4 move.l (4, a1), d0 | Put the starting byte number in d0 addi.l #0x400, d0 | Add the 2 sector offset in the disk for the kernel file -move.l (8, a1), a1 | Put the destination memory address in a1 +move.l (12, a1), a1 | Put the destination memory address in a1 bsr.b read_bytes -move.l a6,a1 | Restore a1 from a6 +move.l a5,a1 | Restore a1 from a5 move.l d4,d0 | Restore d0 from d4 next_seg: lea (0x20, a1), a1 | Advance a1 to point to the next program header dbra d0, phead_loop | If there are more program headers, loop back move.l (PHDR_BUF_START + 0x18), a1 | Load the entry point of the program into a1 +move.l (PHDR_BUF_START + 0x1C), d0 | Load the offset of the program headers in the file +move.l #PHDR_BUF_START, a0 | Put the address of the program headers in a0 +adda.w d0, a0 +move.w (PHDR_BUF_START + 0x2C), d0 | Put the number of program headers in d0 jmp (a1) | Jump to the entry point of the program diff --git a/config.toml b/config.toml index d5347dd..368c715 100644 --- a/config.toml +++ b/config.toml @@ -1,4 +1,4 @@ -symbol_tables = ["boot/boot.elf"] +symbol_tables = ["kernel/kernel.elf"] [[cards]] type = "rom" @@ -9,11 +9,11 @@ type = "term" [[cards]] type = "ram" -size = 65536 +size = 16777216 # 16 MiB [[cards]] type = "storage" image = "os.dsk" -# [[cards]] -# type = "mmu" +[[cards]] +type = "mmu" diff --git a/kernel/kernel.ld b/kernel/kernel.ld index a063d5b..1374d6c 100644 --- a/kernel/kernel.ld +++ b/kernel/kernel.ld @@ -1,220 +1,43 @@ -/* Script for -z combreloc */ -/* Copyright (C) 2014-2022 Free Software Foundation, Inc. - Copying and distribution of this script, with or without modification, - are permitted in any medium without royalty provided the copyright - notice and this notice are preserved. */ -OUTPUT_FORMAT("elf32-m68k", "elf32-m68k", - "elf32-m68k") -OUTPUT_ARCH(m68k) -ENTRY(_start) -SEARCH_DIR("/usr/m68k-elf/lib"); 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+ /* The kernel will live at 12MB in the virtual address space, */ + /* which will be mapped to 0 in the physical address space. */ + /* Note that we page-align the sections. */ + .early.text ALIGN (4K) : { + *(.early.text) + } + .early.rodata ALIGN (4K) : { + *(.early.rodata) + } + .early.data ALIGN (4K) : { + *(.early.data) + } + .early.bss ALIGN (4K) : { + *(.early.bss) + } + + + + . += 0xC00000; + /* Add a symbol that indicates the start address of the kernel. */ + .text ALIGN (4K) : AT (ADDR (.text) - 0xC00000) + { + *(.text) + } + .rodata ALIGN (4K) : AT (ADDR (.rodata) - 0xC00000) + { + *(.rodata) + } + .data ALIGN (4K) : AT (ADDR (.data) - 0xC00000) + { + *(.data) + } + .bss ALIGN (4K) : AT (ADDR (.bss) - 0xC00000) + { + *(COMMON) + *(.bss) + } } diff --git a/kernel/main.68k b/kernel/main.68k index d9c5edf..3e984bb 100644 --- a/kernel/main.68k +++ b/kernel/main.68k @@ -1,5 +1,5 @@ -.global _start -_start: +.global main +main: move.b #'H', 0xFF0200 move.b #'i', 0xFF0200 move.b #0xA, 0xFF0200 diff --git a/kernel/start.68k b/kernel/start.68k new file mode 100644 index 0000000..fcb9b94 --- /dev/null +++ b/kernel/start.68k @@ -0,0 +1,92 @@ +.section .early.text, "ax" +.global _start +| Receives pointer to program headers in a0 and number of program headers in d0 +_start: +move.l d0, d2 +move.l a0, a1 +move.b #0x5, d0 +bsr.w find_first_card_early +cmpa.l #0, a0 +beq.w no_mmu +subq.w #0x1, d2 +phead_loop: +move.l (a1), d1 | If the type of the program header isn't 1 (LOAD), skip the header +cmpi.l #0x1, d1 +bne.b next_phead +| move.b (9, a1), d1 | If the program header is not in the upper quarter, skip it +| cmpi.b #0xc0, d1 +| bgt.b next_phead +move.l (20, a1), d4 | Put the memory size in d4 +move.l d4, d3 +lsr #8, d3 +lsr #4, d3 +andi.l #0xFFF, d4 +cmp.l #0x0, d4 +beq.b even_page +addq.l #1, d3 +even_page: +subq.b #1, d3 +move.l (12, a1), d1 +ori.l #3, d1 +move.l (8, a1), d0 +lsr.l #8, d0 +lsr.l #4, d0 +andi.l #0x3ff, d0 +lsl #2, d0 +move.l #kernel_map, a2 +adda d0, a2 +| d3 contains number of pages - 1 +| d1 initial map entry +| a2 pointer to initial map entry location +map_loop: +move.l d1, (a2)+ +addi.l #0x1000, d1 +dbra d3, map_loop +next_phead: +lea (0x20, a1), a1 | Advance a1 to point to the next program header +dbra d2, phead_loop | If there are more program headers, loop back +io_map: +move.l #15, d0 +move.l #(kernel_map + 0x3f0 * 4), a1 +move.l #0xffff0003, d1 +io_map_loop: +move.l d1, (a1)+ +addi.l #0x1000, d1 +dbra d0, io_map_loop +map_done: +move.l #kernel_map, d0 +ori.l #0x1, d0 +move.l d0, (0x0, a0) +move.l d0, (0xC, a0) +move.w #1, (0x14, a0) +move.w #0, 0xff0000 +move.l #bootstrap_stack, a7 +jmp main +no_mmu: +stop #2700 + +| Finds the first card with the type in d0.b, and returns it's IO base address in a0, or 0 if not found +| Clobbers d1 +find_first_card_early: + move.l #0xff0000, a0 | a0 holds the address of the current card +ffc_early_loop: + lea (0x100, a0), a0 | Move to the next card + move.b (0xff, a0), d1 | Load the type of the card into d1 + beq.b ffc_early_notfound | If the type is 0 (empty slot), we have scanned all cards, so exit the loop + cmp.b d0, d1 | If the card is the type we want, return with the address in a0 + beq.b ffc_early_done + bra.b ffc_early_loop | Loop back and check the next card +ffc_early_notfound: +move.l #0x0, a0 +ffc_early_done: + rts + +.section .early.bss, "aw", @nobits +kernel_map: +.balign 4096 +.ds.b 4096 +kernel_map_end: + +.bss +.ds.b 16384 +bootstrap_stack: