struct tss_struct {
/*
* The hardware state:
*/
struct x86_hw_tss x86_tss;
/*
* The extra 1 is there because the CPU will access an
* additional byte beyond the end of the IO permission
* bitmap. The extra byte must be all 1 bits, and must
* be within the limit.
*/
unsigned long io_bitmap[IO_BITMAP_LONGS + 1];
/*
* .. and then another 0x100 bytes for the emergency kernel stack:
*/
unsigned long stack[64];
} ____cacheline_aligned;
而该结构体的初始化宏为 INIT_TSS 同样也在该文件中。贴出来，代码很明白，
/*
* Note that the .io_bitmap member must be extra-big. This is because
* the CPU will access an additional byte beyond the end of the IO
* permission bitmap. The extra byte must be all 1 bits, and must
* be within the limit.
*/
#define INIT_TSS { \
.x86_tss = { \
.sp0 = sizeof(init_stack) + (long)&init_stack, \
.ss0 = __KERNEL_DS, \
.ss1 = __KERNEL_CS, \
.io_bitmap_base = INVALID_IO_BITMAP_OFFSET, \
}, \
.io_bitmap = { [0 ... IO_BITMAP_LONGS] = ~0 }, \
}
0: kd> dg @tr
P Si Gr Pr Lo
Sel Base Limit Type l ze an es ng Flags
---- -------- -------- ---------- - -- -- -- -- --------
0028 801ed000 000020ab TSS32 Busy 0 Nb By P Nl 0000008b
