[Qemu-devel] [PATCH 2/2] add fw_dir option to option-rom switch

[Glauber Costa <glommer@redhat.com>]

The option-rom puts all roms passed by this switch in the genroms directory,
through the fw_dir option. But as it turns out, not all roms should be placed there.

VGA roms are a of a different kind. They live in a different segment, and are scanned
first. This patch allows qemu to use external vgaroms such as sgabios, a rom for a serial
graphics adapter.

Without this patch, we lose all the initial BIOS output: until the option rom is initialized,
the only available vga rom is the default cirrus/vesa one.

We're also vulnerable to option rom enumeration order: if a vga oprom is initialized
before, say, gpxe, we are able to see its output in the adapter. If it is initialized
after, we miss it.

So I believe the proper solution is to allow users to specify that a rom belongs in vgaroms
directory instead.

Signed-off-by: Glauber Costa <glommer@redhat.com>
CC: Gleb Natapov <gleb@redhat.com>
---
 hw/pc.c         |    7 ++++++-
 qemu-config.c   |    3 +++
 qemu-options.hx |    7 +++++--
 sysemu.h        |    1 +
 vl.c            |    1 +
 5 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/hw/pc.c b/hw/pc.c
index 8d351ba..736efbb 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -1055,7 +1055,12 @@ void pc_memory_init(ram_addr_t ram_size,
     }
 
     for (i = 0; i < nb_option_roms; i++) {
-        rom_add_option(option_rom[i].name, option_rom[i].bootindex);
+        /* do it here, instead of in vl.c, to avoid cluttering that file with x86 material */
+        if (!option_rom[i].fw_dir) {
+            option_rom[i].fw_dir = "genroms";
+        }
+        rom_add_file(option_rom[i].name, option_rom[i].fw_dir, 0,
+                     option_rom[i].bootindex);
     }
 }
 
diff --git a/qemu-config.c b/qemu-config.c
index 6d9c238..97b8515 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -450,6 +450,9 @@ QemuOptsList qemu_option_rom_opts = {
         }, {
             .name = "romfile",
             .type = QEMU_OPT_STRING,
+        }, {
+            .name = "fw_dir",
+            .type = QEMU_OPT_STRING,
         },
         { /* end if list */ }
     },
diff --git a/qemu-options.hx b/qemu-options.hx
index 96927cc..d9eec62 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2079,10 +2079,10 @@ to cope with initialization race conditions.
 ETEXI
 
 DEF("option-rom", HAS_ARG, QEMU_OPTION_option_rom, \
-    "-option-rom rom[,bootindex=idx] load a file, rom, into the option ROM space\n",
+    "-option-rom rom[,bootindex=idx][,fw_dir=dir] load a file, rom, into the option ROM space\n",
     QEMU_ARCH_ALL)
 STEXI
-@item -option-rom @var{file}[,bootindex=@var{bootindex}]
+@item -option-rom @var{file}[,bootindex=@var{bootindex}][,fw_dir=@var{dir}]
 @findex -option-rom
 Load the contents of @var{file} as an option ROM.
 This option is useful to load things like EtherBoot.
@@ -2091,6 +2091,9 @@ This option is useful to load things like EtherBoot.
 @item bootindex=@var{bootindex}
 Defines which boot index the option rom will be given in boot entry vectors,
 allowing fine-grained selection of devices boot order.
+@item fw_dir=@var{dir} (x86 only)
+Specify under which firmware directory entry this rom should live. Current
+allowed values are vgaroms and genroms (default).
 @end table
 
 ETEXI
diff --git a/sysemu.h b/sysemu.h
index 3f7e17e..2f8be32 100644
--- a/sysemu.h
+++ b/sysemu.h
@@ -160,6 +160,7 @@ extern uint64_t node_cpumask[MAX_NODES];
 typedef struct QEMUOptionRom {
     const char *name;
     int32_t bootindex;
+    const char *fw_dir;
 } QEMUOptionRom;
 extern QEMUOptionRom option_rom[MAX_OPTION_ROMS];
 extern int nb_option_roms;
diff --git a/vl.c b/vl.c
index 8bcf2ae..e1d7868 100644
--- a/vl.c
+++ b/vl.c
@@ -2675,6 +2675,7 @@ int main(int argc, char **argv, char **envp)
                     fprintf(stderr, "Option ROM file is not specified\n");
                     exit(1);
                 }
+                option_rom[nb_option_roms].fw_dir = qemu_opt_get(opts, "fw_dir");
 		nb_option_roms++;
 		break;
             case QEMU_OPTION_semihosting:
-- 
1.7.4