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| author | Frans Kaashoek <[email protected]> | 2011-08-09 21:37:35 -0400 |
|---|---|---|
| committer | Frans Kaashoek <[email protected]> | 2011-08-09 21:37:35 -0400 |
| commit | 66ba8079c7e376c189ccb3367b8d13825141b8ec (patch) | |
| tree | 93343a9d7c9ea75a02c05e4ce078ef2d4a48e2da /multiboot.S | |
| parent | 3a038106431314c85a5950c473b113a7037ac1aa (diff) | |
| download | xv6-labs-66ba8079c7e376c189ccb3367b8d13825141b8ec.tar.gz xv6-labs-66ba8079c7e376c189ccb3367b8d13825141b8ec.tar.bz2 xv6-labs-66ba8079c7e376c189ccb3367b8d13825141b8ec.zip | |
Use static page table for boot, mapping first 4Mbyte; no more segment trick
Allocate proper kernel page table immediately in main using boot allocator
Remove pginit
Simplify address space layout a tiny bit
More to come (e.g., superpages to simplify static table)
Diffstat (limited to 'multiboot.S')
| -rw-r--r-- | multiboot.S | 27 |
1 files changed, 14 insertions, 13 deletions
diff --git a/multiboot.S b/multiboot.S index 4aa9f20..84f4aa0 100644 --- a/multiboot.S +++ b/multiboot.S @@ -41,8 +41,8 @@ multiboot_header: # boot loader - bootasm.S - sets up. .globl multiboot_entry multiboot_entry: - lgdt V2P_WO(gdtdesc) - ljmp $(SEG_KCODE<<3), $mbstart32 +# lgdt V2P_WO(gdtdesc) +# ljmp $(SEG_KCODE<<3), $mbstart32 mbstart32: # Set up the protected-mode data segment registers @@ -54,21 +54,22 @@ mbstart32: movw %ax, %fs # -> FS movw %ax, %gs # -> GS + movl $(V2P_WO(bootpgdir)), %eax + movl %eax, %cr3 + # Turn on paging. + movl %cr0, %eax + orl $(CR0_PE|CR0_PG|CR0_WP), %eax + movl %eax, %cr0 + + # now switch to using addresses above KERNBASE + # call addresses are pc-relative so we jump though this hoop: + mov $relocated, %eax + jmp *%eax +relocated: # Set up the stack pointer and call into C. movl $(stack + STACK), %esp call main spin: jmp spin -# Bootstrap GDT -.p2align 2 # force 4 byte alignment -gdt: - SEG_NULLASM # null seg - SEG_ASM(STA_X|STA_R, -KERNBASE, 0xffffffff) # code seg - SEG_ASM(STA_W, -KERNBASE, 0xffffffff) # data seg - -gdtdesc: - .word (gdtdesc - gdt - 1) # sizeof(gdt) - 1 - .long V2P_WO(gdt) # address gdt - .comm stack, STACK |