From 430252a4c700cc77eafeb91aec3ef609e8c625ca Mon Sep 17 00:00:00 2001
From: mikl <mikl@iscg.dev>
Date: Fri, 26 Jun 2026 03:05:01 +0300
Subject: [PATCH] muscari: switch bootloader from systemd-boot (UEFI) to GRUB
 (BIOS)

VM 81.26.189.192 boots in Legacy BIOS mode (PREREQUISITES.md
check 5+11 returned BIOS / NO_EFI), so UEFI/systemd-boot is not
available. Switched to GRUB on /dev/vda.

Changes:
- boot.loader.grub.enable = true, device = "/dev/vda"
- boot.loader.systemd-boot.enable = lib.mkForce false
- boot.loader.efi.canTouchEfiVariables = lib.mkForce false
- Comments updated to reflect BIOS / GRUB choice

disk-config.nix NOT touched: the 512M ESP at /boot is unused in
BIOS mode (GRUB installs to MBR), but harmless. If we later switch
to UEFI, the ESP will be ready.

Verification:
- nix flake show: nixosConfigurations.muscari
- boot.loader.grub.enable = true
- boot.loader.systemd-boot.enable = false
- fileSystems: /boot (vfat ESP) + / (ext4 root) from disko

Session: verify plan
---
 hosts/muscari/default.nix | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/hosts/muscari/default.nix b/hosts/muscari/default.nix
index b201bcd..e8de8c6 100644
--- a/hosts/muscari/default.nix
+++ b/hosts/muscari/default.nix
@@ -20,9 +20,17 @@
     ];
   };
 
-  # Bootloader — systemd-boot (UEFI, требуется для YC standard-v3)
-  boot.loader.systemd-boot.enable = true;
-  boot.loader.efi.canTouchEfiVariables = true;
+  # Bootloader — GRUB (BIOS, VM в legacy boot mode)
+  # VM 81.26.189.192 загружается в Legacy BIOS (check 5+11 в PREREQUISITES.md),
+  # поэтому UEFI/systemd-boot недоступен. ESP раздел в disk-config.nix
+  # не используется (GRUB ставится в MBR /dev/vda), но и не мешает.
+  boot.loader.grub = {
+    enable = true;
+    device = "/dev/vda";
+    useOSProber = false;
+  };
+  boot.loader.systemd-boot.enable = lib.mkForce false;
+  boot.loader.efi.canTouchEfiVariables = lib.mkForce false;
 
   # fileSystems — определяется через disko (см. disk-config.nix)
   # Не задаём явно fileSystems."/" чтобы не конфликтовать с disko