Use a single _payload_offset linker-defined variable to locate the

start of the non-prefix blocks in the loaded image, and rely on the
image ordering.  This should make introducing compression much easier.

diff --git a/src/arch/i386/prefix/libprefix.S b/src/arch/i386/prefix/libprefix.S
index 0253121..d155451 100644 (file)
--- a/src/arch/i386/prefix/libprefix.S
+++ b/src/arch/i386/prefix/libprefix.S
@@ -49,14 +49,14 @@
  * Install block to specified address
  *
  * Parameters:
- *   %esi : byte offset within loaded image (must be a multiple of 16)
+ *   %esi : start offset within loaded image (must be a multiple of 16)
  *   %es:edi : destination address
  *   %ecx : length of (decompressed) data
  *   %edx : total length of block (including any uninitialised data portion)
  * Returns:
- *   none
+ *   %esi : end offset within image (rounded up to next multiple of 16)
  * Corrupts:
- *   %esi, %edi, %ecx, %edx
+ *   %edi, %ecx, %edx
  ****************************************************************************
  */
        .section ".prefix.lib"
@@ -65,6 +65,8 @@ install_block:
        /* Preserve registers */
        pushw   %ds
        pushl   %eax
+       pushl   %ebx
+       movl    %esi, %ebx
        
        /* Starting segment => %ds */
        movw    %cs, %ax
@@ -87,7 +89,13 @@ install_block:
        xorb    %al, %al
        rep addr32 stosb
 
+       /* Adjust %esi */
+       addl    %ebx, %esi
+       addl    $0xf, %esi
+       andl    $~0xf, %esi
+
        /* Restore registers */
+       popl    %ebx
        popl    %eax
        popw    %ds
        ret
@@ -144,8 +152,9 @@ alloc_basemem:
  * Parameters: 
  *   %ax : .text16 segment address
  *   %bx : .data16 segment address
+ *   %esi : start offset within loaded image (must be a multiple of 16)
  * Returns:
- *   none
+ *   %esi : end offset within image (rounded up to next multiple of 16)
  * Corrupts:
  *   none
  ****************************************************************************
@@ -155,7 +164,6 @@ alloc_basemem:
 install_basemem:
        /* Preserve registers */
        pushw   %es
-       pushl   %esi
        pushl   %edi
        pushl   %ecx
        pushl   %edx
@@ -163,7 +171,6 @@ install_basemem:
        /* Install .text16 */
        movw    %ax, %es
        xorl    %edi, %edi
-       movl    $_text16_load_offset, %esi
        movl    $_text16_size, %ecx
        movl    %ecx, %edx
        call    install_block
@@ -171,7 +178,6 @@ install_basemem:
        /* Install .data16 */
        movw    %bx, %es
        xorl    %edi, %edi      
-       movl    $_data16_load_offset, %esi
        movl    $_data16_progbits_size, %ecx
        movl    $_data16_size, %edx
        call    install_block
@@ -180,7 +186,6 @@ install_basemem:
        popl    %edx
        popl    %ecx
        popl    %edi
-       popl    %esi
        popw    %es
        ret
        .size install_basemem, . - install_basemem
@@ -191,9 +196,10 @@ install_basemem:
  * Install .text and .data into high memory
  *
  * Parameters:
+ *   %esi : start offset within loaded image (must be a multiple of 16)
  *   %es:edi : address in high memory
  * Returns:
- *   none
+ *   %esi : end offset within image (rounded up to next multiple of 16)
  * Corrupts:
  *   none
  ****************************************************************************
@@ -205,13 +211,11 @@ install_basemem:
        .code16
 install_highmem:
        /* Preserve registers */
-       pushl   %esi
        pushl   %edi
        pushl   %ecx
        pushl   %edx
                
        /* Install .text and .data to specified address */
-       movl    $_textdata_load_offset, %esi
        movl    $_textdata_progbits_size, %ecx
        movl    $_textdata_size, %edx
        call    install_block
@@ -220,7 +224,6 @@ install_highmem:
        popl    %edx
        popl    %ecx
        popl    %edi
-       popl    %esi
        ret
        .size install_highmem, . - install_highmem
        
@@ -343,7 +346,10 @@ install:
        .size install, . - install
        .globl install_prealloc
 install_prealloc:
+       /* Save registers */
+       pushl   %esi
        /* Install .text16 and .data16 */
+       movl    $_payload_offset, %esi
        call    install_basemem
 
 #ifdef KEEP_IT_REAL
@@ -358,14 +364,13 @@ install_prealloc:
        pushfw
        pushw   %ds
        pushw   %es
-       pushl   %esi
        pushl   %ecx
        cli
 
        /* Load up %ds and %es, and set up vectors for far calls to .text16 */
        movw    %bx, %ds
-       xorw    %si, %si
-       movw    %si, %es
+       xorw    %cx, %cx
+       movw    %cx, %es
        movw    %ax, (init_librm_vector+2)
        movw    %ax, (prot_call_vector+2)
        
@@ -401,11 +406,11 @@ install_prealloc:
 
        /* Restore registers and interrupt status */
        popl    %ecx
-       popl    %esi
        popw    %es
        popw    %ds
        popfw
 #endif
+       popl    %esi
        ret
        .size install_prealloc, . - install_prealloc
 

diff --git a/src/arch/i386/scripts/i386.lds b/src/arch/i386/scripts/i386.lds
index 287c6ba..7b7b95d 100644 (file)
--- a/src/arch/i386/scripts/i386.lds
+++ b/src/arch/i386/scripts/i386.lds
@@ -215,6 +215,8 @@ SECTIONS {
 
     _load_size             = . - _load_addr;
 
+    _payload_offset        = _text16_load_offset;
+
     /*
      * Alignment checks.  ALIGN() can only operate on the location
      * counter, so we set the location counter to each value we want