[romprefix] Store boot bus:dev.fn address as autoboot device location

Per the BIOS Boot Specification, the initialization phase of the ROM is called with the PFA (PCI Function Address) in the %ax register. The intention is that the ROM code will store that device address somewhere and use it for booting from that device when the Boot Entry Vector (BEV) is called. iPXE does store the PFA, but doesn't use it to select the boot network device. This renders BIOS IPL lists fairly ineffective. Fix by using the BBS-specified bus:dev.fn address as the autoboot device location. Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Modified-by: Michael Brown <mcb30@ipxe.org> Signed-off-by: Michael Brown <mcb30@ipxe.org>
ipxe · Mar 3, 2014 · c429bf0 · c429bf0
1 parent 90fc273
commit c429bf0
Showing 1 changed file with 11 additions and 1 deletion.
diff --git a/src/arch/i386/prefix/romprefix.S b/src/arch/i386/prefix/romprefix.S
@@ -738,7 +738,17 @@ exec:	/* Set %ds = %cs */
 	pushw	$1f
 	lret
 	.section ".text16", "awx", @progbits
-1:	/* Call main() */
+1:
+	/* Retrieve PCI bus:dev.fn */
+	movw	init_pci_busdevfn, %cx
+
+	/* Set up %ds for access to .data16 */
+	movw	%bx, %ds
+
+	/* Store PCI bus:dev.fn */
+	movw	%cx, autoboot_busdevfn
+
+	/* Call main() */
 	pushl	$main
 	pushw	%cs
 	call	prot_call