[Xen-devel] [PATCH v2 2/3] x86: a little bit of 16-bit video mode setting code cleanup

[Jan Beulich <jbeulich@suse.com>]

To "compensate" for the code size growth by an earlier change:
- drop "trampoline" labels (in almost all cases the target label is
  reachable with an 8-bit-displacement branch anyway, and a single 16-
  bit-displacement branch is still better than a pair of two branches)
- drop an entirely dead insn from wakeup.S:mode_setw
- reduce code size in a few other (obvious I hope) cases, by more
  suitable insn/operands selection

Also drop redundant #define-s (move suitable #include a little earlier
instead) and add two alignment directives.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v2: Minor adjustment to description. Re-base.

--- a/xen/arch/x86/boot/trampoline.S
+++ b/xen/arch/x86/boot/trampoline.S
@@ -176,6 +176,7 @@ start64:
 
         jmpq    *%rdi
 
+#include "video.h"
 #include "wakeup.S"
 
         .balign 8
@@ -282,8 +283,6 @@ trampoline_boot_cpu_entry:
         /* Jump to the common bootstrap entry point. */
         jmp     trampoline_protmode_entry
 
-#include "video.h"
-
         .align  2
 /* Keep in sync with cmdline.c:early_boot_opts_t type! */
 early_boot_opts:
--- a/xen/arch/x86/boot/video.S
+++ b/xen/arch/x86/boot/video.S
@@ -384,9 +384,6 @@ lmbad:  leaw    bootsym(unknt), %si
         jmp     mode_menu
 lmdef:  ret
 
-_setrec:    jmp setrec                  # Ugly...
-_set_80x25: jmp set_80x25
-
 # Setting of user mode (AX=mode ID) => CF=success
 mode_set:
         movw    %ax, bootsym(boot_vid_mode)
@@ -396,7 +393,7 @@ mode_set:
         je      setvesabysize
 
         testb   $VIDEO_RECALC>>8, %ah
-        jnz     _setrec
+        jnz     setrec
 
         cmpb    $VIDEO_FIRST_SPECIAL>>8, %ah
         jz      setspc
@@ -421,7 +418,7 @@ setspc: xorb    %bh, %bh
 
 setmenu:
         orb     %al, %al                # 80x25 is an exception
-        jz      _set_80x25
+        jz      set_80x25
         
         pushw   %bx                     # Set mode chosen from menu
         call    mode_table              # Build the mode table
@@ -441,36 +438,32 @@ check_vesa:
         cmpw    $0x004f, %ax
         jnz     setbad
 
-        leaw    vesa_mode_info, %di
-        subb    $VIDEO_FIRST_VESA>>8, %bh
-        movw    %bx, %cx                # Get mode information structure
+        leaw    vesa_mode_info, %di     # Get mode information structure
+        leaw    -VIDEO_FIRST_VESA(%bx), %cx
         movw    $0x4f01, %ax
         int     $0x10
-        addb    $VIDEO_FIRST_VESA>>8, %bh
         cmpw    $0x004f, %ax
         jnz     setbad
 
         movb    (%di), %al              # Check mode attributes.
         andb    $0x99, %al
         cmpb    $0x99, %al
-        jnz     _setbad                 # Doh! No linear frame buffer.
+        jnz     setbad                  # Doh! No linear frame buffer.
 
         pushw   %bx
         subb    $VIDEO_FIRST_VESA>>8, %bh
-        orw     $0x4000, %bx            # Use linear frame buffer
+        orb     $0x40, %bh              # Use linear frame buffer
         movw    $0x4f02, %ax            # VESA BIOS mode set call
         int     $0x10
         popw    %bx
         cmpw    $0x004f, %ax            # AL=4f if implemented
-        jnz     _setbad                 # AH=0 if OK
+        jnz     setbad                  # AH=0 if OK
 
         movb    $1, bootsym(graphic_mode)  # flag graphic mode
         movw    %bx, bootsym(video_mode)
         stc
         ret
 
-_setbad: jmp    setbad                  # Ugly...
-
 # Recalculate vertical display end registers -- this fixes various
 # inconsistencies of extended modes on many adapters. Called when
 # the VIDEO_RECALC flag is set in the mode ID.
@@ -515,7 +508,7 @@ setvesabysize:
         leaw    modelist,%si
 1:      add     $8,%si
         cmpw    $ASK_VGA,-8(%si)        # End?
-        je      _setbad
+        je      setbad
         movw    -6(%si),%ax
         cmpw    %ax,bootsym(vesa_size)+0
         jne     1b
@@ -948,6 +941,7 @@ store_edid:
 #endif
         ret
 
+                .p2align 1
 mt_end:         .word   0       # End of video mode table if built
 edit_buf:       .space  6       # Line editor buffer
 card_name:      .word   0       # Pointer to adapter name
@@ -991,6 +985,7 @@ vesa_name:      .asciz  "VESA"
 
 name_bann:      .asciz  "Video adapter: "
 
+                .p2align 1
 force_size:     .word   0       # Use this size instead of the one in BIOS vars
 
 GLOBAL(boot_vid_info)
--- a/xen/arch/x86/boot/wakeup.S
+++ b/xen/arch/x86/boot/wakeup.S
@@ -30,7 +30,7 @@ ENTRY(wakeup_start)
         jne     bogus_real_magic
 
         # for acpi_sleep=s3_bios
-        testl   $1, wakesym(video_flags)
+        testb   $1, wakesym(video_flags)
         jz      1f
         lcall   $0xc000, $3
         movw    %cs, %ax        # In case messed by BIOS
@@ -38,9 +38,9 @@ ENTRY(wakeup_start)
         movw    %ax, %ss        # Need this? How to ret if clobbered?
 
 1:      # for acpi_sleep=s3_mode
-        testl   $2, wakesym(video_flags)
+        testb   $2, wakesym(video_flags)
         jz      1f
-        movl    wakesym(video_mode), %eax
+        movw    wakesym(video_mode), %ax
         call    mode_setw
 
 1:      # Show some progress if VGA is resumed
@@ -56,48 +56,26 @@ ENTRY(wakeup_start)
 
         ljmpl   $BOOT_CS32, $bootsym_rel(wakeup_32, 6)
 
-/* This code uses an extended set of video mode numbers. These include:
- * Aliases for standard modes
- *      NORMAL_VGA (-1)
- *      EXTENDED_VGA (-2)
- *      ASK_VGA (-3)
- * Video modes numbered by menu position -- NOT RECOMMENDED because of lack
- * of compatibility when extending the table. These are between 0x00 and 0xff.
- */
-#define VIDEO_FIRST_MENU 0x0000
-
-/* Standard BIOS video modes (BIOS number + 0x0100) */
-#define VIDEO_FIRST_BIOS 0x0100
-
-/* VESA BIOS video modes (VESA number + 0x0200) */
-#define VIDEO_FIRST_VESA 0x0200
-
-/* Video7 special modes (BIOS number + 0x0900) */
-#define VIDEO_FIRST_V7 0x0900
-
 # Setting of user mode (AX=mode ID) => CF=success
 mode_setw:
         movw    %ax, %bx
         cmpb    $VIDEO_FIRST_VESA>>8, %ah
         jnc     check_vesaw
-        decb    %ah
 
 setbadw: clc
         ret
 
 check_vesaw:
         subb    $VIDEO_FIRST_VESA>>8, %bh
-        orw     $0x4000, %bx                    # Use linear frame buffer
+        orb     $0x40, %bh                      # Use linear frame buffer
         movw    $0x4f02, %ax                    # VESA BIOS mode set call
         int     $0x10
         cmpw    $0x004f, %ax                    # AL=4f if implemented
-        jnz     _setbadw                        # AH=0 if OK
+        jnz     setbadw                         # AH=0 if OK
 
         stc
         ret
 
-_setbadw: jmp    setbadw
-
 bogus_real_magic:
         movw    $0x0e00 + 'B', %fs:(0x12)
         jmp     bogus_real_magic


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