[Qemu-devel] [PATCH 1/6] pc: initialize fw_cfg earlier

[Paolo Bonzini <pbonzini@redhat.com>]

Notifiers are called in LIFO order.  In our case, we want fw_cfg to use
the output of the machine-specific notifier: we will process the -kernel
command-line option there, and this will modify the boot order which
fw_cfg's notifier processes.

Because fw_cfg's notifier has to run last, we have to create the device
early, before pc_guest_info_init registers its own notifier.

It turns out that pc_guest_info_init is itself a good place to create
fw_cfg.  This also makes Xen more similar to native machine types.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/i386/pc.c | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index b6c9b61..b95ac18 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -104,6 +104,8 @@ static struct e820_entry *e820_table;
 static unsigned e820_entries;
 struct hpet_fw_config hpet_cfg = {.count = UINT8_MAX};
 
+static FWCfgState *bochs_bios_init(void);
+
 void gsi_handler(void *opaque, int n, int level)
 {
     GSIState *s = opaque;
@@ -1093,6 +1095,9 @@ PcGuestInfo *pc_guest_info_init(ram_addr_t below_4g_mem_size,
     PcGuestInfo *guest_info = &guest_info_state->info;
     int i, j;
 
+    guest_info->fw_cfg = bochs_bios_init();
+    rom_set_fw(guest_info->fw_cfg);
+
     guest_info->ram_size_below_4g = below_4g_mem_size;
     guest_info->ram_size = below_4g_mem_size + above_4g_mem_size;
     guest_info->apic_id_limit = pc_apic_id_limit(max_cpus);
@@ -1173,22 +1178,17 @@ FWCfgState *xen_load_linux(const char *kernel_filename,
                            PcGuestInfo *guest_info)
 {
     int i;
-    FWCfgState *fw_cfg;
 
     assert(kernel_filename != NULL);
 
-    fw_cfg = fw_cfg_init(BIOS_CFG_IOPORT, BIOS_CFG_IOPORT + 1, 0, 0);
-    rom_set_fw(fw_cfg);
-
-    load_linux(fw_cfg, kernel_filename, initrd_filename,
+    load_linux(guest_info->fw_cfg, kernel_filename, initrd_filename,
                kernel_cmdline, below_4g_mem_size);
     for (i = 0; i < nb_option_roms; i++) {
         assert(!strcmp(option_rom[i].name, "linuxboot.bin") ||
                !strcmp(option_rom[i].name, "multiboot.bin"));
         rom_add_option(option_rom[i].name, option_rom[i].bootindex);
     }
-    guest_info->fw_cfg = fw_cfg;
-    return fw_cfg;
+    return guest_info->fw_cfg;
 }
 
 FWCfgState *pc_memory_init(MachineState *machine,
@@ -1202,7 +1202,7 @@ FWCfgState *pc_memory_init(MachineState *machine,
     int linux_boot, i;
     MemoryRegion *ram, *option_rom_mr;
     MemoryRegion *ram_below_4g, *ram_above_4g;
-    FWCfgState *fw_cfg;
+    FWCfgState *fw_cfg = guest_info->fw_cfg;
     PCMachineState *pcms = PC_MACHINE(machine);
 
     assert(machine->ram_size == below_4g_mem_size + above_4g_mem_size);
@@ -1280,9 +1280,6 @@ FWCfgState *pc_memory_init(MachineState *machine,
                                         option_rom_mr,
                                         1);
 
-    fw_cfg = bochs_bios_init();
-    rom_set_fw(fw_cfg);
-
     if (guest_info->has_reserved_memory && pcms->hotplug_memory_base) {
         uint64_t *val = g_malloc(sizeof(*val));
         *val = cpu_to_le64(ROUND_UP(pcms->hotplug_memory_base, 0x1ULL << 30));
@@ -1297,7 +1294,6 @@ FWCfgState *pc_memory_init(MachineState *machine,
     for (i = 0; i < nb_option_roms; i++) {
         rom_add_option(option_rom[i].name, option_rom[i].bootindex);
     }
-    guest_info->fw_cfg = fw_cfg;
     return fw_cfg;
 }
 
-- 
2.1.0