[prefix] Add A20-enabling code in libflat

[people/meteger/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 df71a9d..6a23a96 100644 (file)
--- a/src/arch/i386/prefix/libprefix.S
+++ b/src/arch/i386/prefix/libprefix.S
@@ -512,13 +512,24 @@ install_prealloc:
 
        /* Open up access to payload */
 #ifndef KEEP_IT_REAL
 
        /* Open up access to payload */
 #ifndef KEEP_IT_REAL

-       /* Flatten real mode */
+       /* Access high memory */

        pushw   %cs
        pushw   $1f
        pushw   %ax
        pushw   %cs
        pushw   $1f
        pushw   %ax

-       pushw   $flatten_real_mode
+       pushw   $access_highmem

        lret
        lret

-1:
+1:     /* Die if we could not access high memory */
+       jnc     3f
+       movw    $a20_death_message, %si
+       xorw    %di, %di
+       call    print_message
+2:     jmp     2b
+       .section ".prefix.data", "aw", @progbits
+a20_death_message:
+       .asciz  "Gate A20 stuck - cannot continue\n"
+       .size   a20_death_message, . - a20_death_message
+       .previous
+3:

 #endif
 
        /* Calculate physical address of payload (i.e. first source) */
 #endif
 
        /* Calculate physical address of payload (i.e. first source) */


@@ -570,13 +581,13 @@ install_prealloc:
        popl    %edx /* discard */
 
        /* Copy code to new location */
        popl    %edx /* discard */
 
        /* Copy code to new location */

+       pushl   %edi

        xorw    %ax, %ax
        movw    %ax, %es
        xorw    %ax, %ax
        movw    %ax, %es

-       movl    %ebp, %edi

        es rep addr32 movsb
        es rep addr32 movsb

+       popl    %edi

 
        /* Initialise librm at new location */
 
        /* Initialise librm at new location */

-       movl    %ebp, %edi

        lcall   *init_librm_vector
 #endif
 
        lcall   *init_librm_vector
 #endif