Extend validate_bootloader_layout with UEFI-dependent checks (#4474)

* Extend validate_bootloader_layout with UEFI-dependent checks

Add is_uefi parameter and three new validations: Systemd-boot, Efistub
and rEFInd require UEFI; Efistub additionally requires a FAT boot
partition. Move the rEFInd UEFI-only check out of GlobalMenu so
guided.py and Installer silent-install paths get the same coverage.

* Encapsulate UEFI-only flag in Bootloader enum

Replace module-level _UEFI_ONLY_BOOTLOADERS tuple with an
is_uefi_only() method on the Bootloader enum, mirroring the
existing has_uki_support() / has_removable_support() pattern.

* Drop is_uefi parameter from validate_bootloader_layout

The UEFI flag is a constant system fact for the run, so the
validator retrieves it via SysInfo.has_uefi() directly instead
of having every caller pass it in. Updates all three call sites
in global_menu.py, installer.py and guided.py, and removes the
now-unused SysInfo import from guided.py.

archinstall/lib/bootloader/utils.py

@@ -2,6 +2,7 @@ from dataclasses import dataclass
 from enum import Enum, auto
 from pathlib import Path
 
+from archinstall.lib.hardware import SysInfo
 from archinstall.lib.models.bootloader import Bootloader, BootloaderConfiguration
 from archinstall.lib.models.device import DiskLayoutConfiguration
 
@@ -9,6 +10,8 @@ from archinstall.lib.models.device import DiskLayoutConfiguration
 class BootloaderValidationFailureKind(Enum):
 	LimineNonFatBoot = auto()
 	LimineLayout = auto()
+	BootloaderRequiresUefi = auto()
+	EfistubNonFatBoot = auto()
 
 
 @dataclass(frozen=True)
@@ -29,12 +32,32 @@ def validate_bootloader_layout(
 	if not (bootloader_config and disk_config):
 		return None
 
-	if bootloader_config.bootloader == Bootloader.Limine:
-		boot_part = next(
-			(p for m in disk_config.device_modifications if (p := m.get_boot_partition())),
-			None,
+	bootloader = bootloader_config.bootloader
+
+	if bootloader == Bootloader.NO_BOOTLOADER:
+		return None
+
+	if bootloader.is_uefi_only() and not SysInfo.has_uefi():
+		return BootloaderValidationFailure(
+			kind=BootloaderValidationFailureKind.BootloaderRequiresUefi,
+			description=f'{bootloader.value} requires a UEFI system.',
 		)
 
+	boot_part = next(
+		(p for m in disk_config.device_modifications if (p := m.get_boot_partition())),
+		None,
+	)
+
+	if bootloader == Bootloader.Efistub:
+		# The UEFI firmware reads the kernel directly from the boot partition,
+		# which must be FAT.
+		if boot_part and (boot_part.fs_type is None or not boot_part.fs_type.is_fat()):
+			return BootloaderValidationFailure(
+				kind=BootloaderValidationFailureKind.EfistubNonFatBoot,
+				description='Efistub does not support booting with a non-FAT boot partition.',
+			)
+
+	if bootloader == Bootloader.Limine:
 		# Limine reads its config and kernels from the boot partition, which
 		# must be FAT.
 		if boot_part and (boot_part.fs_type is None or not boot_part.fs_type.is_fat()):

archinstall/lib/global_menu.py

@@ -461,8 +461,6 @@ class GlobalMenu(AbstractMenu[None]):
 		if not bootloader_config or bootloader_config.bootloader == Bootloader.NO_BOOTLOADER:
 			return None
 
-		bootloader = bootloader_config.bootloader
-
 		if disk_config := self._item_group.find_by_key('disk_config').value:
 			for layout in disk_config.device_modifications:
 				if root_partition := layout.get_root_partition():
@@ -490,9 +488,6 @@ class GlobalMenu(AbstractMenu[None]):
 			if efi_partition.fs_type is None or not efi_partition.fs_type.is_fat():
 				return 'ESP must be formatted as a FAT filesystem'
 
-		if bootloader == Bootloader.Refind and not self._uefi:
-			return 'rEFInd can only be used on UEFI systems'
-
 		if failure := validate_bootloader_layout(bootloader_config, disk_config):
 			return failure.description
 

archinstall/lib/models/bootloader.py

@@ -25,6 +25,13 @@ class Bootloader(Enum):
 			case _:
 				return False
 
+	def is_uefi_only(self) -> bool:
+		match self:
+			case Bootloader.Systemd | Bootloader.Efistub | Bootloader.Refind:
+				return True
+			case _:
+				return False
+
 	def json(self) -> str:
 		return self.value