[romprefix] Inhibit the use of relocation during POST

[gpxe.git] / src / arch / i386 / prefix / libprefix.S

diff --git a/src/arch/i386/prefix/libprefix.S b/src/arch/i386/prefix/libprefix.S
index f5f6691..eeed0ad 100644 (file)
--- a/src/arch/i386/prefix/libprefix.S
+++ b/src/arch/i386/prefix/libprefix.S
@@ -443,6 +443,8 @@ install:
        xorl    %esi, %esi
        /* Image destination = default */
        xorl    %edi, %edi
        xorl    %esi, %esi
        /* Image destination = default */
        xorl    %edi, %edi

+       /* Allow relocation */
+       clc

        /* Install text and data segments */
        call    install_prealloc
        /* Restore registers and return */
        /* Install text and data segments */
        call    install_prealloc
        /* Restore registers and return */


@@ -461,6 +463,7 @@ install:
  *   %bx  : .data16 segment address
  *   %esi : Image source physical address (or zero for %cs:0000)
  *   %edi : Decompression temporary area physical address (or zero for default)
  *   %bx  : .data16 segment address
  *   %esi : Image source physical address (or zero for %cs:0000)
  *   %edi : Decompression temporary area physical address (or zero for default)

+ *   CF set : Avoid relocating to top of memory

  * Corrupts:
  *   none
  ****************************************************************************
  * Corrupts:
  *   none
  ****************************************************************************


@@ -473,9 +476,8 @@ install_prealloc:
        pushal
        pushw   %ds
        pushw   %es
        pushal
        pushw   %ds
        pushw   %es

-
-       /* Sanity: clear the direction flag asap */
-       cld
+       cld                     /* Sanity: clear the direction flag asap */
+       pushfw

 
        /* Copy decompression temporary area physical address to %ebp */
        movl    %edi, %ebp
 
        /* Copy decompression temporary area physical address to %ebp */
        movl    %edi, %ebp


@@ -570,6 +572,11 @@ a20_death_message:
        movl    %ebp, %edi
        lcall   *init_librm_vector
 
        movl    %ebp, %edi
        lcall   *init_librm_vector
 

+       /* Skip relocation if CF was set on entry */
+       popfw
+       pushfw
+       jc      skip_relocate
+

        /* Call relocate() to determine target address for relocation.
         * relocate() will return with %esi, %edi and %ecx set up
         * ready for the copy to the new location.
        /* Call relocate() to determine target address for relocation.
         * relocate() will return with %esi, %edi and %ecx set up
         * ready for the copy to the new location.


@@ -588,9 +595,11 @@ a20_death_message:
 
        /* Initialise librm at new location */
        lcall   *init_librm_vector
 
        /* Initialise librm at new location */
        lcall   *init_librm_vector

+skip_relocate:

 #endif
 
        /* Restore registers */
 #endif
 
        /* Restore registers */

+       popfw

        popw    %es
        popw    %ds
        popal
        popw    %es
        popw    %ds
        popal