Understanding the linux kernel-ch3-Process Switch

task switch
context switch
hardware context
switch_to Macro
#define switch_to(prev,next,last) do {					/
	unsigned long esi,edi;						/
	asm volatile("pushfl/n/t"					/
		"pushl %%ebp/n/t"					/
		"movl %%esp,%0/n/t"	/* save ESP */		/
		"movl %5,%%esp/n/t"	/* restore ESP */	/
		"movl $1f,%1/n/t"		/* save EIP */		/
		"pushl %6/n/t"		/* restore EIP */	/
		"jmp __switch_to/n"				/
		"1:/t"						/
		"popl %%ebp/n/t"					/
		"popfl"						/
		:"=m" (prev->thread.esp),"=m" (prev->thread.eip),	/
		"=a" (last),"=S" (esi),"=D" (edi)			/
		:"m" (next->thread.esp),"m" (next->thread.eip),	/
		"2" (prev), "d" (next));				/
} while (0)
1. movl prev, %eax
movl next, %edx
2. pushfl
pushl %ebp
3,movl %esp,484(%eax)		//prev->thread.esp
4,movl 484(%edx), %esp		//next->thread.esp
5,movl $1f, 480(%eax)		//prev->thread.eip
6,pushl 480(%edx)		//next->thread.eip
7,jmp _ _switch_to
8. 1:
popl %ebp
popfl
9,movl %eax, last
_ _switch_to ( )
_ _switch_to(struct task_struct *prev_p,
struct task_struct *next_p)
_ _attribute_ _(regparm(3));
	_ _unlazy_fpu( ) macro,save the contents of the FPU, MMX, and XMM registers of the prev_p process.
	smp_processor_id( ) macro to get the index of the local CPU
	Loads next_p->thread.esp0 in the esp0 field of the TSS relative to the local CPU
	Loads in the Global Descriptor Table of the local CPU the Thread-Local Storage (TLS) segments used by the next_p process
	Stores the contents of the fs and gs segmentation registers in prev_p->thread.fs and prev_p->thread.gs
	load fs or the gs segmentation register
	Loads six of the dr0,..., dr7 debug registers
	Updates the I/O bitmap in the TSS
	Terminates
FPU:arithmetic floating-point unit
	floating-point registers belongs to hardware context				ESCAPE
MMX instructions act on the floating-point registers of the FPU
SIMD:	single-instruction multiple-data
SSE extensions		Streaming SIMD Extensions			Pentium III
XMM registers
SSE2 extensions			Pentium 4
TS (Task-Switching) flag in the cr0 register