[SeaBIOS] [PATCH 3/3] vgahooks: Create 155f50 hook.

From: Julian Pidancet

This patch adds a 155f50 hook which is mandatory for VGA option ROM to
work on some platforms. This allows an Intel GFX device to be passed
through to a Xen VM on some laptops using a Dell BIOS (Tested
successfully on a Dell Lattitude E6410 laptop).

Signed-off-by: Julian Pidancet 
---
 src/vgahooks.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/src/vgahooks.c b/src/vgahooks.c
index ca12e31..3ae50e5 100644
--- a/src/vgahooks.c
+++ b/src/vgahooks.c
@@ -187,11 +187,20 @@ intel_155f40(struct bregs *regs)
 }

static void
+intel_155f50(struct bregs *regs)
+{
+    /* Mandatory hook on some Dell laptops */
+    regs->ax = 0x005f;
+    set_success(regs);
+}
+
+static void
 intel_155f(struct bregs *regs)
 {
     switch (regs->al) {
     case 0x35: intel_155f35(regs); break;
     case 0x40: intel_155f40(regs); break;
+    case 0x50: intel_155f50(regs); break;
     default:   handle_155fXX(regs); break;
     }
 }