Messages in this thread | | | Date | Wed, 20 Feb 2002 13:26:18 -0800 | From | Jason Yan <> | Subject | paging question |
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Hi,
I have a question about the code to enable to initialize page tables in linux/arch/i386/head.S
I search the internet again and again but fail to find any answer so far, maybe you gurus can help me out, here it goes:
48 cld 49 movl $(__KERNEL_DS),%eax 50 movl %eax,%ds 51 movl %eax,%es 52 movl %eax,%fs 53 movl %eax,%gs 81 /* 82 * Initialize page tables 83 */ 84 movl $pg0-__PAGE_OFFSET,%edi /* initialize page tables */ 85 movl $007,%eax /* "007" doesn't mean with right to kill, but 86 PRESENT+RW+USER */ 87 2: stosl 88 add $0x1000,%eax 89 cmp $empty_zero_page-__PAGE_OFFSET,%edi 90 jne 2b I remove the SMP code. According the setup.S, gdt_table is setup as gdt_table: #.quad 0x0000000000000000; // null #.quad 0x0000000000000000; // not used #.quad 0x00cf9a000000ffff; // 0x10 kernel 4GB code at 0x00000000 #.quad 0x00cf92000000ffff; // 0x18 kernel 4GB data at 0x00000000
1) So, what's in %eax after line 49 ? 0x0 ? 2) Isn't __PAGE_OFFSET 0xC0000000 ? what's the result of $pg0-__PAGE_OFFSET ?
Thanks,
Jason
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