[gnome-boxes/disable-efi] Disable creation of VMs with EFI firmware

[Felipe Borges <felipeborges src gnome org>]

commit c486da262f6566326fbcb5ef45c5f64048f16a6e
Author: Felipe Borges <felipeborges gnome org>
Date:   Tue Jun 2 13:16:42 2020 +0200

    Disable creation of VMs with EFI firmware
    
    Once upon a time we were very excited about introducing EFI support
    in GNOME Boxes. It seemed like the right thing to do, there was a
    vocal group of users requesting it.
    https://gitlab.gnome.org/GNOME/gnome-boxes/-/issues/199
    
    Unfortunately, we were not aware at the time of the existing
    limitations that it would introduce to our user experience. The most
    critical one is undoubtedly support for snapshots.
    
    Snapshots are one of the top selling features of GNOME Boxes. They
    allow for reverting a virtual machine guest to a desired state in
    time, including memory state. This is extremely useful for our users
    that use VMs for system's development. Oftentimes they will perform
    tasks which can leave their guests in a broken state, and snapshots
    are here to save them.
    
    Internal snapshots are really a migration to disk, this means that for
    EFI you might end up trying to migrate to the backing store of the
    nvram device. Therefore libvirt will scream:
    "Operation not supported: internal snapshots of a VM with pflash based
    firmware are not supported".
    
    External snapshots can handle EFI. Except they don't. :) External
    snapshots partially work for EFI guests. They can store the EFI state
    in the memory image but we can't revert the guest to a given snapshot.
    ¯\_(ツ)_/¯
    
    In the words of one of the libvirt developers "there was no time to
    do it because of seemingly shinier features".
    
    In my personal quest to workaround this issue, I attempted to use
    internal snapshots storing DISK_ONLY content. No memory. That's
    already a feature regression for us, but what can we do, right?
    Everybody seems to want UEFI! It turns out that once you create an
    internal snapshot with the DISK_ONLY flag, your snapshots become
    external. So yep, no reverting.
    
    All in all, I don't have a way to end this saga in a high note.
    We are going to stop creating guests with EFI in the 3.36.x series,
    and for 3.38 we will only create EFI guests for those operating
    systems that libosinfo reports to support ONLY EFI. These guests
    need EFI to boot, so in this case they won't have snapshots. For
    the great majority of OSes that support BIOS, snapshots will
    continue to exist and make our lives easier. The end.
    
    Signed-off-by: Felipe Borges <felipeborges gnome org>

 meson_options.txt        |  5 -----
 src/installer-media.vala | 14 --------------
 src/meson.build          |  3 ---
 src/vm-configurator.vala | 34 +++-------------------------------
 src/vm-creator.vala      |  3 +--
 5 files changed, 4 insertions(+), 55 deletions(-)
---
diff --git a/meson_options.txt b/meson_options.txt
index a5f1be87..c55a4712 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -29,8 +29,3 @@ option ('profile',
   ],
   value: 'default'
 )
-
-option ('uefi',
-        type: 'boolean',
-        value: true,
-        description: 'Use UEFI whenever it is possible')
diff --git a/src/installer-media.vala b/src/installer-media.vala
index ffae48ac..d2500750 100644
--- a/src/installer-media.vala
+++ b/src/installer-media.vala
@@ -55,20 +55,6 @@
         }
     }
 
-    public bool supports_efi {
-        get {
-            if (os == null)
-                return false;
-
-            foreach (var iter in os.get_firmware_list (null) .get_elements ()) {
-                var firmware = iter as Firmware;
-                if (firmware.get_firmware_type () == "efi")
-                    return true;
-            }
-            return false;
-        }
-    }
-
     public virtual bool prefers_q35 {
         get {
             if (os == null)
diff --git a/src/meson.build b/src/meson.build
index 56e9874e..75a3cc29 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -194,9 +194,6 @@ else
   dependencies += libovf.get_variable('govf_vapi')
 endif
 
-if get_option('uefi')
-    vala_args += '--define=USE_UEFI'
-endif
 
 executable ('gnome-boxes', vala_sources + resources,
             include_directories: config_h_dir,
diff --git a/src/vm-configurator.vala b/src/vm-configurator.vala
index 32fa5cba..a7d7180b 100644
--- a/src/vm-configurator.vala
+++ b/src/vm-configurator.vala
@@ -38,7 +38,7 @@
     private const string LIBOSINFO_XML = "<libosinfo>%s</libosinfo>";
     private const string LIBOSINFO_OS_ID_XML = "<os id=\"%s\"/>";
 
-    public static Domain create_domain_config (InstallerMedia install_media, string target_path, 
Capabilities caps, DomainCapabilities domain_caps)
+    public static Domain create_domain_config (InstallerMedia install_media, string target_path, 
Capabilities caps)
                                         throws VMConfiguratorError {
         var domain = new Domain ();
 
@@ -51,7 +51,7 @@ public static Domain create_domain_config (InstallerMedia install_media, string
         var virt_type = guest_kvm_enabled (best_caps) ? DomainVirtType.KVM : DomainVirtType.QEMU;
         domain.set_virt_type (virt_type);
 
-        set_os_config (domain, install_media, best_caps, domain_caps);
+        set_os_config (domain, install_media, best_caps);
 
         string[] features = {};
         if (guest_supports_feature (best_caps, "acpi"))
@@ -375,45 +375,17 @@ private static void set_post_install_os_config (Domain domain) {
 
         os.set_arch (old_os.get_arch ());
         os.set_machine (old_os.get_machine ());
-#if USE_UEFI
-        if (old_os.get_firmware () == GVirConfig.DomainOsFirmware.EFI)
-            os.set_firmware (GVirConfig.DomainOsFirmware.EFI);
-#endif
 
         domain.set_os (os);
     }
 
-    private static bool domain_caps_supports_efi (DomainCapabilities domain_caps) {
-        foreach (var firmware in domain_caps.get_os ().get_firmwares()) {
-            if (firmware == GVirConfig.DomainOsFirmware.EFI)
-                return true;
-        }
-
-        return false;
-    }
-
-    private static bool supports_efi (InstallerMedia install_media, DomainCapabilities domain_caps) {
-        if (install_media == null || !install_media.supports_efi)
-            return false;
-
-        if (domain_caps == null || !domain_caps_supports_efi (domain_caps))
-            return false;
-
-        return true;
-    }
-
-    private static void set_os_config (Domain domain, InstallerMedia install_media, CapabilitiesGuest 
guest_caps, DomainCapabilities domain_caps) {
+    private static void set_os_config (Domain domain, InstallerMedia install_media, CapabilitiesGuest 
guest_caps) {
         var os = new DomainOs ();
         os.set_os_type (DomainOsType.HVM);
         os.set_arch (guest_caps.get_arch ().get_name ());
         if (install_media.prefers_q35)
             os.set_machine ("q35");
 
-#if USE_UEFI
-        if (supports_efi (install_media, domain_caps))
-            os.set_firmware (GVirConfig.DomainOsFirmware.EFI);
-#endif
-
         var boot_devices = new GLib.List<DomainOsBootDevice> ();
         install_media.set_direct_boot_params (os);
         boot_devices.append (DomainOsBootDevice.CDROM);
diff --git a/src/vm-creator.vala b/src/vm-creator.vala
index 2aa58b76..b958be9c 100644
--- a/src/vm-creator.vala
+++ b/src/vm-creator.vala
@@ -192,8 +192,7 @@ protected void set_post_install_config (LibvirtMachine machine) {
                                                                     StorageVol   volume,
                                                                     Cancellable? cancellable) throws 
GLib.Error {
         var caps = yield connection.get_capabilities_async (cancellable);
-        var domcaps = yield connection.get_domain_capabilities_async (null, null, null, null, 0, 
cancellable);
-        var config = VMConfigurator.create_domain_config (install_media, volume.get_path (), caps, domcaps);
+        var config = VMConfigurator.create_domain_config (install_media, volume.get_path (), caps);
         config.name = name;
         config.title = title;