Linux Kernel Architecture

Mauerer runapp01.tex V1 - 09/04/2008 6:08pm Page 1124

Appendix A: Architecture Specifics

long twd;

long fip;

long fcs;

long foo;

long fos;

long st_space[20]; /* 8*10 bytes for each FP-reg = 80 bytes */

long status; /* software status information */

};

More recent processor versions use slightly wider registers and also support a second set of registers

known as XMM.

include/asm-x86/processor_32.h

struct i387_fxsave_struct {

u16 cwd;

u16 swd;

u16 twd;

u16 fop;

u64 rip;

u64 rdp;

u32 mxcsr;

u32 mxcsr_mask;

u32 st_space[32]; /* 8*16 bytes for each FP-reg = 128 bytes */

u32 xmm_space[64]; /* 16*16 bytes for each XMM-reg = 128 bytes */

u32 padding[24];

} __attribute__ ((aligned (16)));

A.7.2 IA-64

In the design of IA-64, the designated successor of the aging IA-32 architecture, Intel has kept abreast of

the times and has given the processor a much bigger register set (with a more systematic name).

include/asm-ia64/processor.h
struct pt_regs {
/ The following registers are saved by SAVE_MIN: /
unsigned long b6; / scratch /
unsigned long b7; / scratch /

unsigned long ar_csd; /* used by cmp8xchg16 (scratch) */

unsigned long ar_ssd; /* reserved for future use (scratch) */

unsigned long r8; /* scratch (return value register 0) */

unsigned long r9; /* scratch (return value register 1) */

unsigned long r10; /* scratch (return value register 2) */

unsigned long r11; /* scratch (return value register 3) */

unsigned long cr_ipsr; /* interrupted task’s psr */

unsigned long cr_iip; /* interrupted task’s instruction pointer */

/*

* interrupted task’s function state; if bit 63 is cleared, it

* contains syscall’s ar.pfs.pfm:

*/

unsigned long cr_ifs;