x86: add comments to processor.h

add comments to the FPU structures of processor.h.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 28 insertions, 23 deletions

diff --git a/include/asm-x86/processor.h b/include/asm-x86/processor.h
index e49e5e69ebb0..1f9501a38493 100644
--- a/include/asm-x86/processor.h
+++ b/include/asm-x86/processor.h
@@ -289,42 +289,47 @@ struct orig_ist {
 #define MXCSR_DEFAULT           0x1f80
 
 struct i387_fsave_struct {
-        u32                     cwd;
-        u32                     swd;
-        u32                     twd;
-        u32                     fip;
-        u32                     fcs;
-        u32                     foo;
-        u32                     fos;
-        /* 8*10 bytes for each FP-reg = 80 bytes: */
+        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;
-        /* 8*16 bytes for each FP-reg = 128 bytes: */
+        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: */
+
+        /* 16*16 bytes for each XMM-reg = 256 bytes:                    */
         u32                     xmm_space[64];
+
         u32                     padding[24];
 
 } __attribute__((aligned(16)));