Don't trash the %ecx value returned by relocate(). This was causing

us to round down the size for the relocation copy to the nearest 64kB
(+0x10 bytes); this just happened to work on most machines because the
last 64kB of the image is all-zeroes anyway (it's the .bss).

diff --git a/src/arch/i386/prefix/libprefix.S b/src/arch/i386/prefix/libprefix.S
index f146d3d..26ec752 100644 (file)
--- a/src/arch/i386/prefix/libprefix.S
+++ b/src/arch/i386/prefix/libprefix.S
@@ -277,7 +277,7 @@ gdt_end:
  * Sets limits on the data segments %ds and %es.
  *
  * Parameters:
- *   %cx : segment type (FLAT_DS for 4GB or REAL_DS for 64kB)
+ *   %dx : segment type (FLAT_DS for 4GB or REAL_DS for 64kB)
  ****************************************************************************
  */
 
@@ -309,8 +309,8 @@ set_real_mode_limits:
        movl    %eax, %cr0
 
        /* Set flat segment limits */
-       movw    %cx, %ds
-       movw    %cx, %es
+       movw    %dx, %ds
+       movw    %dx, %es
 
        /* Switch back to real mode */
        movl    %cr0, %eax
@@ -355,6 +355,7 @@ install:
 install_prealloc:
        /* Save registers */
        pushl   %esi
+       pushw   %dx
        /* Install .text16 and .data16 */
        movl    $_payload_offset, %esi
        call    install_basemem
@@ -385,7 +386,7 @@ install_prealloc:
         * prior to reading the E820 memory map and relocating
         * properly.
         */
-       movw    $FLAT_DS, %cx
+       movw    $FLAT_DS, %dx
        call    set_real_mode_limits
        movl    $HIGHMEM_LOADPOINT, %edi
        call    install_highmem
@@ -400,7 +401,7 @@ install_prealloc:
        addw    $4, %sp
 
        /* Move code to new location, set up new protected-mode GDT */
-       movw    $FLAT_DS, %cx
+       movw    $FLAT_DS, %dx
        call    set_real_mode_limits
        pushl   %edi
        es rep addr32 movsb
@@ -408,7 +409,7 @@ install_prealloc:
        lcall   *init_librm_vector
 
        /* Restore real-mode segment limits */
-       movw    $REAL_DS, %cx
+       movw    $REAL_DS, %dx
        call    set_real_mode_limits
 
        /* Restore registers and interrupt status */
@@ -417,6 +418,7 @@ install_prealloc:
        popw    %ds
        popfw
 #endif
+       popw    %dx
        popl    %esi
        ret
        .size install_prealloc, . - install_prealloc