[romprefix] Remove special treatment for IBM BIOSes

Revert commit 38cd351 ("[romprefix] Attempt to gracefully handle
semi-PnP IBM BIOSes"), since the test for the "IBM " signature in %edi
is not sufficient to identify an IBM BIOS.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/arch/i386/prefix/romprefix.S b/src/arch/i386/prefix/romprefix.S
index 49fd24b9a446a54cb5f6b32d6bd615574e34bb6a..dd602ddb7108fb6afa0805a312208dd830437bd1 100644 (file)
--- a/src/arch/i386/prefix/romprefix.S
+++ b/src/arch/i386/prefix/romprefix.S
@@ -13,7 +13,6 @@ FILE_LICENCE ( GPL2_OR_LATER )
 #define PNP_SIGNATURE ( '$' + ( 'P' << 8 ) + ( 'n' << 16 ) + ( 'P' << 24 ) )
 #define PMM_SIGNATURE ( '$' + ( 'P' << 8 ) + ( 'M' << 16 ) + ( 'M' << 24 ) )
 #define PCI_SIGNATURE ( 'P' + ( 'C' << 8 ) + ( 'I' << 16 ) + ( ' ' << 24 ) )
-#define IBM_SIGNATURE ( ( 'I' << 24 ) + ( 'B' << 16 ) + ( 'M' << 8 ) + ' ' )
 #define STACK_MAGIC ( 'L' + ( 'R' << 8 ) + ( 'E' << 16 ) + ( 'T' << 24 ) )
 #define PMM_ALLOCATE 0x0000
 #define PMM_FIND 0x0001
@@ -173,7 +172,6 @@ undiheader:
 init:
        /* Preserve registers, clear direction flag, set %ds=%cs */
        pushaw
-       pushl   %ebx
        pushw   %ds
        pushw   %es
        pushw   %fs
@@ -182,14 +180,15 @@ init:
        pushw   %cs
        popw    %ds
 
-       /* Shuffle some registers around.  We need to use %di for the
-        * print_xxx functions, so shuffle as follows:
+       /* Shuffle some registers around.  We need %di available for
+        * the print_xxx functions, and in a register that's
+        * addressable from %es, so shuffle as follows:
         *
+        *    %di (pointer to PnP structure) => %bx
         *    %bx (runtime segment address, for PCI 3.0) => %gs
-        *    %edi (IBM signature) => %ebx
         */
        movw    %bx, %gs
-       movl    %edi, %ebx
+       movw    %di, %bx
 
        /* Store PCI bus:dev.fn address */
        movw    %ax, init_pci_busdevfn
@@ -264,16 +263,7 @@ no_pci3:
        popl    %edx
        popl    %ebx
 
-       /* Check for IBM BIOS, which uses the PnP entry points but
-        * doesn't indicate PnP support.
-        */
-       cmpl    $IBM_SIGNATURE, %ebx
-       jne     no_ibm
-       movw    $init_message_ibm, %si
-       xorw    %di, %di
-       call    print_message
-       jmp     pnp_done
-no_ibm:        /* Check for PnP BIOS.  Although %es:di should point to the
+       /* Check for PnP BIOS.  Although %es:di should point to the
         * PnP BIOS signature on entry, some BIOSes fail to do this.
         */
        movw    $( 0xf000 - 1 ), %bx
@@ -426,7 +416,6 @@ no_pmm:
        popw    %fs
        popw    %es
        popw    %ds
-       popl    %ebx
        popaw
 
        /* Indicate boot capability to PnP BIOS, if present */
@@ -541,9 +530,6 @@ init_message:
 init_message_pci:
        .asciz  " PCI"
        .size   init_message_pci, . - init_message_pci
-init_message_ibm:
-       .asciz  " IBM"
-       .size   init_message_ibm, . - init_message_ibm
 init_message_pnp:
        .asciz  " PnP"
        .size   init_message_pnp, . - init_message_pnp