x86: add comments to processor.h

#define	MXCSR_DEFAULT		0x1f80

struct i387_fsave_struct {

	u32			cwd;

	u32			swd;

	u32			twd;

	u32			fip;

	u32			fcs;

	u32			foo;

	u32			fos;

	u32			cwd;	/* FPU Control Word		*/

	u32			swd;	/* FPU Status Word		*/

	u32			twd;	/* FPU Tag Word			*/

	u32			fip;	/* FPU IP Offset		*/

	u32			fcs;	/* FPU IP Selector		*/

	u32			foo;	/* FPU Operand Pointer Offset	*/

	u32			fos;	/* FPU Operand Pointer Selector	*/

	/* 8*10 bytes for each FP-reg = 80 bytes:			*/

	u32			st_space[20];

	/* Software status information: */

	/* Software status information [not touched by FSAVE ]:		*/

	u32			status;

};

struct i387_fxsave_struct {

	u16			cwd;

	u16			swd;

	u16			twd;

	u16			fop;

	u16			cwd; /* Control Word			*/

	u16			swd; /* Status Word			*/

	u16			twd; /* Tag Word			*/

	u16			fop; /* Last Instruction Opcode		*/

	union {

		struct {

			u64	rip;

			u64	rdp;

			u64	rip; /* Instruction Pointer		*/

			u64	rdp; /* Data Pointer			*/

		};

		struct {

			u32	fip;

			u32	fcs;

			u32	foo;

			u32	fos;

			u32	fip; /* FPU IP Offset			*/

			u32	fcs; /* FPU IP Selector			*/

			u32	foo; /* FPU Operand Offset		*/

			u32	fos; /* FPU Operand Selector		*/

		};

	};

	u32			mxcsr;

	u32			mxcsr_mask;

	u32			mxcsr;		/* MXCSR Register State */

	u32			mxcsr_mask;	/* MXCSR Mask		*/

	/* 8*16 bytes for each FP-reg = 128 bytes:			*/

	u32			st_space[32];

	/* 16*16 bytes for each XMM-reg = 256 bytes:			*/

	u32			xmm_space[64];

	u32			padding[24];

} __attribute__((aligned(16)));