Avoid code addresses >64K in big real mode.

Kvm has some limitations with code addresses in big real mode, so
avoid doing that.

diff --git a/src/misc.c b/src/misc.c
index 354df87502486215de9cd8e4ae391b7c6b415547..108c3326e34ac7002860b9d3d15e0e69898be3cb 100644 (file)
--- a/src/misc.c
+++ b/src/misc.c
@@ -156,8 +156,8 @@ u64 rombios32_gdt[] VAR16VISIBLE __aligned(8) = {
     GDT_LIMIT(BUILD_BIOS_SIZE-1) | GDT_CODE | GDT_BASE(BUILD_BIOS_ADDR),
     // 16 bit data segment base=0x0 limit=0xffff (SEG32_MODE16_DS)
     GDT_LIMIT(0x0ffff) | GDT_DATA,
-    // 16 bit code segment base=0 limit=0xffffffff (SEG32_MODE16BIG_CS)
-    GDT_LIMIT(0xfffff) | GDT_CODE | GDT_G,
+    // 16 bit code segment base=0xf0000 limit=0xffffffff (SEG32_MODE16BIG_CS)
+    GDT_LIMIT(0xfffff) | GDT_CODE | GDT_G | GDT_BASE(BUILD_BIOS_ADDR),
     // 16 bit data segment base=0 limit=0xffffffff (SEG32_MODE16BIG_DS)
     GDT_LIMIT(0xfffff) | GDT_DATA | GDT_G,
 };

diff --git a/src/romlayout.S b/src/romlayout.S
index 54e5a4d25a3b246e46bfd5eea07b68eea4b42cd6..a4695963cd4b10d1369273aef36562eb7f00dd65 100644 (file)
--- a/src/romlayout.S
+++ b/src/romlayout.S
@@ -105,7 +105,7 @@ transition16big:
         movw %ax, %fs
         movw %ax, %gs
 
-        ljmpl $SEG32_MODE16BIG_CS, $(BUILD_BIOS_ADDR + 1f)
+        ljmpw $SEG32_MODE16BIG_CS, $1f
 
         .code16gcc
 1: