Linux uses three GDTs to boot: the boot_gdt_table, which contains only
the __BOOT_CS and __BOOT_DS entries is used first up, before kernel is
mapped at PAGE_OFFSET. Then we transition to cpu_gdt_table during
boot, and finally we allocate a per-cpu GDT and switch to that.
We can simplify this by using the boot_gdt_table until switching to
the per-cpu GDT table. As a bonus, this gets rid of the
horribly-named "cpu_gdt_table" (it's not per-cpu, and the T in GDT
already stands for table).
Finally, some old bogus comments are deleted.
Signed-off-by: Rusty Russell <[EMAIL PROTECTED]>
diff -r 9cf03cbf8bde arch/i386/kernel/cpu/common.c
--- a/arch/i386/kernel/cpu/common.c Thu Mar 01 16:40:41 2007 +1100
+++ b/arch/i386/kernel/cpu/common.c Thu Mar 01 21:58:16 2007 +1100
@@ -694,7 +694,7 @@ __cpuinit int init_gdt(int cpu, struct t
* Initialize the per-CPU GDT with the boot GDT,
* and set up the GDT descriptor:
*/
- memcpy(gdt, cpu_gdt_table, GDT_SIZE);
+ memcpy(gdt, boot_gdt_table, GDT_SIZE);
cpu_gdt_descr->size = GDT_SIZE - 1;
pack_descriptor((u32 *)&gdt[GDT_ENTRY_PDA].a,
diff -r 9cf03cbf8bde arch/i386/kernel/head.S
--- a/arch/i386/kernel/head.S Thu Mar 01 16:40:41 2007 +1100
+++ b/arch/i386/kernel/head.S Thu Mar 01 22:05:37 2007 +1100
@@ -595,31 +595,19 @@ idt_descr:
.word IDT_ENTRIES*8-1 # idt contains 256 entries
.long idt_table
-# boot GDT descriptor (later on used by CPU#0):
+# The boot GDT descriptor once paging is enabled.
.word 0 # 32 bit align gdt_desc.address
ENTRY(early_gdt_descr)
.word GDT_ENTRIES*8-1
- .long cpu_gdt_table
-
-/*
- * The boot_gdt_table must mirror the equivalent in setup.S and is
- * used only for booting.
- */
+ .long boot_gdt_table
+
+/* The boot Global Descriptor Table: after boot we allocate a per-cpu copy */
.align L1_CACHE_BYTES
ENTRY(boot_gdt_table)
- .fill GDT_ENTRY_BOOT_CS,8,0
- .quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */
- .quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */
-
-/*
- * The Global Descriptor Table contains 28 quadwords, per-CPU.
- */
- .align L1_CACHE_BYTES
-ENTRY(cpu_gdt_table)
.quad 0x0000000000000000 /* NULL descriptor */
.quad 0x0000000000000000 /* 0x0b reserved */
- .quad 0x0000000000000000 /* 0x13 reserved */
- .quad 0x0000000000000000 /* 0x1b reserved */
+ .quad 0x00cf9a000000ffff /* boot: 4GB code at 0x00000000 */
+ .quad 0x00cf92000000ffff /* boot: 4GB data at 0x00000000 */
.quad 0x0000000000000000 /* 0x20 unused */
.quad 0x0000000000000000 /* 0x28 unused */
.quad 0x0000000000000000 /* 0x33 TLS entry 1 */
diff -r 9cf03cbf8bde include/asm-i386/desc.h
--- a/include/asm-i386/desc.h Thu Mar 01 16:40:41 2007 +1100
+++ b/include/asm-i386/desc.h Thu Mar 01 21:57:37 2007 +1100
@@ -12,7 +12,7 @@
#include <asm/mmu.h>
-extern struct desc_struct cpu_gdt_table[GDT_ENTRIES];
+extern struct desc_struct boot_gdt_table[GDT_ENTRIES];
struct Xgt_desc_struct {
unsigned short size;
-
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