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Kernel: Make resizing the page tables for the kernel image easier

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By using the KERNEL_PD_OFFSET constant we can avoid some of the
hard-coded values in the boot code.
This commit is contained in:
Gunnar Beutner 2021-07-16 10:05:34 +02:00 • committed by Andreas Kling
parent cbdb488578
commit a17c25e45e
1 changed files with 9 additions and 26 deletions
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35
Kernel/Arch/x86/common/Boot/boot.S
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@ -34,7 +34,7 @@ boot_pd0_pt0:
.skip 4096 * 4
.global boot_pd3_pts
boot_pd3_pts:
.skip 4096 * 16
.skip 4096 * (KERNEL_PD_OFFSET >> 21)
.global boot_pd3_pt1023
boot_pd3_pt1023:
.skip 4096
@ -65,33 +65,16 @@ pdpt
2: n/a (2-3GB)
3: boot_pd3 (3-4GB)
boot_pd0 : 512 pde's
boot_pd0 : 512 PDEs
0: boot_pd0_pt0 (0-2MB) (id 512 4KB pages)
boot_pd3 : 512 pde's
boot_pd3 : 512 PDEs
0: boot_pd3_pts[0] (3072-3074MB) (pseudo 512 4KB pages)
1: boot_pd3_pts[1] (3074-3076MB) (pseudo 512 4KB pages)
2: boot_pd3_pts[2] (3076-3078MB) (pseudo 512 4KB pages)
3: boot_pd3_pts[3] (3078-3080MB) (pseudo 512 4KB pages)
4: boot_pd3_pts[4] (3080-3082MB) (pseudo 512 4KB pages)
5: boot_pd3_pts[5] (3082-3084MB) (pseudo 512 4KB pages)
6: boot_pd3_pts[6] (3084-3086MB) (pseudo 512 4KB pages)
7: boot_pd3_pts[7] (3086-3088MB) (pseudo 512 4KB pages)
8: boot_pd3_pts[8] (3088-3090MB) (pseudo 512 4KB pages)
9: boot_pd3_pts[9] (3090-3076MB) (pseudo 512 4KB pages)
10: boot_pd3_pts[10] (3092-3094MB) (pseudo 512 4KB pages)
11: boot_pd3_pts[11] (3094-3096MB) (pseudo 512 4KB pages)
12: boot_pd3_pts[12] (3096-3098MB) (pseudo 512 4KB pages)
13: boot_pd3_pts[13] (3098-3100MB) (pseudo 512 4KB pages)
14: boot_pd3_pts[14] (3100-3102MB) (pseudo 512 4KB pages)
15: boot_pd3_pts[15] (3102-3104MB) (pseudo 512 4KB pages)
boot_pd3_pts[*] (KERNEL_BASE to KERNEL_BASE + KERNEL_PD_OFFSET) (pseudo 512 4KB pages)
last entry: boot_pd3_pt1023 (4094-4096MB) (for page table mappings)
16: boot_pd3_pt1023 (4094-4096MB) (for page table mappings)
the 9 page tables each contain 512 pte's that map individual 4KB pages
the page tables each contain 512 PTEs that map individual 4KB pages
*/
@ -445,7 +428,7 @@ pae_supported:
orl $0x3, 0(%edi)
/* add boot_pd3_pts to boot_pd3 */
movl $16, %ecx
movl $(KERNEL_PD_OFFSET >> 21), %ecx
movl $(boot_pd3 - KERNEL_BASE), %edi
movl $(boot_pd3_pts - KERNEL_BASE), %eax
@ -470,8 +453,8 @@ pae_supported:
addl $4096, %eax
loop 1b
/* pseudo identity map the 3072-3104MB range */
movl $(512 * 16), %ecx
/* pseudo identity map the KERNEL_BASE to KERNEL_BASE + KERNEL_PD_OFFSET range */
movl $(512 * (KERNEL_PD_OFFSET >> 21)), %ecx
movl $(boot_pd3_pts - KERNEL_BASE), %edi
xorl %eax, %eax