As the bios is a ROM, just using rom API.
AFAICS no functionality changed.

Signed-off-by: Li Qiang <liq3ea@gmail.com>
---
 hw/i386/pc_sysfw.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
index 091e22dd60..7f469fd582 100644
--- a/hw/i386/pc_sysfw.c
+++ b/hw/i386/pc_sysfw.c
@@ -209,9 +209,9 @@ static void old_pc_system_rom_init(MemoryRegion *rom_memory, bool isapc_ram_fw)
         goto bios_error;
     }
     bios = g_malloc(sizeof(*bios));
-    memory_region_init_ram(bios, NULL, "pc.bios", bios_size, &error_fatal);
-    if (!isapc_ram_fw) {
-        memory_region_set_readonly(bios, true);
+    memory_region_init_rom(bios, NULL, "pc.bios", bios_size, &error_fatal);
+    if (isapc_ram_fw) {
+        memory_region_set_readonly(bios, false);
     }
     ret = rom_add_file_fixed(bios_name, (uint32_t)(-bios_size), -1);
     if (ret != 0) {
@@ -230,8 +230,8 @@ static void old_pc_system_rom_init(MemoryRegion *rom_memory, bool isapc_ram_fw)
                                         0x100000 - isa_bios_size,
                                         isa_bios,
                                         1);
-    if (!isapc_ram_fw) {
-        memory_region_set_readonly(isa_bios, true);
+    if (isapc_ram_fw) {
+        memory_region_set_readonly(isa_bios, false);
     }
 
     /* map all the bios at the top of memory */
-- 
2.11.0

On 09/10/2018 07:55, Li Qiang wrote:
> As the bios is a ROM, just using rom API.
> AFAICS no functionality changed.
> 
> Signed-off-by: Li Qiang <liq3ea@gmail.com>
> ---

ROM and RAM are just the same, with the readonly flag defaulting to
either true or false.

Because the alias here:

    memory_region_init_alias(isa_bios, NULL, "isa-bios", bios,
                             bios_size - isa_bios_size, isa_bios_size);
    if (!isapc_ram_fw) {
        memory_region_set_readonly(isa_bios, true);
    }

defaults to read-write (and your patch is wrong in changing the
direction of the if), it makes sense to do the same for the bios memory
region.

Thanks,

Paolo