Add a fd-bootchk property to PC machine types, so that -no-fd-bootchk
returns an error if the machine does not support booting from floppies
and checking for boot signatures therein.

Suggested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 include/hw/i386/pc.h |  2 +-
 hw/i386/pc.c         | 31 ++++++++++++++++++++++++++-----
 system/globals.c     |  1 -
 system/vl.c          |  2 +-
 qemu-options.hx      |  2 +-
 5 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index e88468131a5..034bef25f58 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -50,6 +50,7 @@ typedef struct PCMachineState {
     bool hpet_enabled;
     bool i8042_enabled;
     bool default_bus_bypass_iommu;
+    bool fd_bootchk;
     uint64_t max_fw_size;
 
     /* ACPI Memory hotplug IO base address */
@@ -147,7 +148,6 @@ OBJECT_DECLARE_TYPE(PCMachineState, PCMachineClass, PC_MACHINE)
 GSIState *pc_gsi_create(qemu_irq **irqs, bool pci_enabled);
 
 /* pc.c */
-extern int fd_bootchk;
 
 void pc_acpi_smi_interrupt(void *opaque, int irq, int level);
 
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index f8eb684a492..ea3607452af 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -399,8 +399,8 @@ static int boot_device2nibble(char boot_device)
     return 0;
 }
 
-static void set_boot_dev(MC146818RtcState *s, const char *boot_device,
-                         Error **errp)
+static void set_boot_dev(PCMachineState *pcms, MC146818RtcState *s,
+                         const char *boot_device, Error **errp)
 {
 #define PC_MAX_BOOT_DEVICES 3
     int nbds, bds[3] = { 0, };
@@ -420,12 +420,14 @@ static void set_boot_dev(MC146818RtcState *s, const char *boot_device,
         }
     }
     mc146818rtc_set_cmos_data(s, 0x3d, (bds[1] << 4) | bds[0]);
-    mc146818rtc_set_cmos_data(s, 0x38, (bds[2] << 4) | (fd_bootchk ? 0x0 : 0x1));
+    mc146818rtc_set_cmos_data(s, 0x38, (bds[2] << 4) | !pcms->fd_bootchk);
 }
 
 static void pc_boot_set(void *opaque, const char *boot_device, Error **errp)
 {
-    set_boot_dev(opaque, boot_device, errp);
+    PCMachineState *pcms = PC_MACHINE(current_machine);
+
+    set_boot_dev(pcms, opaque, boot_device, errp);
 }
 
 static void pc_cmos_init_floppy(MC146818RtcState *rtc_state, ISADevice *floppy)
@@ -619,7 +621,7 @@ void pc_cmos_init(PCMachineState *pcms,
     object_property_set_link(OBJECT(pcms), "rtc_state", OBJECT(s),
                              &error_abort);
 
-    set_boot_dev(s, MACHINE(pcms)->boot_config.order, &error_fatal);
+    set_boot_dev(pcms, s, MACHINE(pcms)->boot_config.order, &error_fatal);
 
     val = 0;
     val |= 0x02; /* FPU is there */
@@ -1543,6 +1545,20 @@ static void pc_machine_set_vmport(Object *obj, Visitor *v, const char *name,
     visit_type_OnOffAuto(v, name, &pcms->vmport, errp);
 }
 
+static bool pc_machine_get_fd_bootchk(Object *obj, Error **errp)
+{
+    PCMachineState *pcms = PC_MACHINE(obj);
+
+    return pcms->fd_bootchk;
+}
+
+static void pc_machine_set_fd_bootchk(Object *obj, bool value, Error **errp)
+{
+    PCMachineState *pcms = PC_MACHINE(obj);
+
+    pcms->fd_bootchk = value;
+}
+
 static bool pc_machine_get_smbus(Object *obj, Error **errp)
 {
     PCMachineState *pcms = PC_MACHINE(obj);
@@ -1731,6 +1747,7 @@ static void pc_machine_initfn(Object *obj)
 #ifdef CONFIG_HPET
     pcms->hpet_enabled = true;
 #endif
+    pcms->fd_bootchk = true;
     pcms->default_bus_bypass_iommu = false;
 
     pcms->pcspk = isa_new(TYPE_PC_SPEAKER);
@@ -1878,6 +1895,10 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
         NULL, NULL);
     object_class_property_set_description(oc, PC_MACHINE_SMBIOS_EP,
         "SMBIOS Entry Point type [32, 64]");
+
+    object_class_property_add_bool(oc, "fd-bootchk",
+        pc_machine_get_fd_bootchk,
+        pc_machine_set_fd_bootchk);
 }
 
 static const TypeInfo pc_machine_info = {
diff --git a/system/globals.c b/system/globals.c
index b6d4e72530e..5d0046ba105 100644
--- a/system/globals.c
+++ b/system/globals.c
@@ -41,7 +41,6 @@ int vga_interface_type = VGA_NONE;
 bool vga_interface_created;
 Chardev *parallel_hds[MAX_PARALLEL_PORTS];
 int win2k_install_hack;
-int fd_bootchk = 1;
 int graphic_rotate;
 QEMUOptionRom option_rom[MAX_OPTION_ROMS];
 int nb_option_roms;
diff --git a/system/vl.c b/system/vl.c
index b8469d9965d..98bf0c386b4 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -2927,7 +2927,7 @@ void qemu_init(int argc, char **argv)
                           optarg, FD_OPTS);
                 break;
             case QEMU_OPTION_no_fd_bootchk:
-                fd_bootchk = 0;
+                qdict_put_str(machine_opts_dict, "fd-bootchk", "off");
                 break;
             case QEMU_OPTION_netdev:
                 default_net = 0;
diff --git a/qemu-options.hx b/qemu-options.hx
index 9be1e5817c7..1136642c21d 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2650,7 +2650,7 @@ DEF("no-fd-bootchk", 0, QEMU_OPTION_no_fd_bootchk,
 SRST
 ``-no-fd-bootchk``
     Disable boot signature checking for floppy disks in BIOS. May be
-    needed to boot from old floppy disks.
+    needed to boot from old floppy disks.  Synonym of ``-m fd-bootchk=off``.
 ERST
 
 DEF("acpitable", HAS_ARG, QEMU_OPTION_acpitable,
-- 
2.43.2