install: Don't require EFI if booted via BIOS and doing alongside

Today Anaconda defaults to setting up the bootloader with
source == target mode; on x86_64 that means if booted via BIOS
the system is installed just with BIOS, and EFI if booted via EFI.

When we're doing an alongside install we hence cannot require
an ESP.

Signed-off-by: Colin Walters <walters@verbum.org>

Author: cgwalters

lib/src/bootloader.rs

@@ -1,4 +1,5 @@
 use std::os::unix::prelude::PermissionsExt;
+use std::path::Path;
 
 use anyhow::{Context, Result};
 use camino::Utf8Path;
@@ -51,20 +52,43 @@ fn install_grub2_efi(efidir: &Dir, uuid: &str) -> Result<()> {
     Ok(())
 }
 
+/// Return `true` if the system is booted via EFI
+pub(crate) fn is_efi_booted() -> Result<bool> {
+    if !super::install::ARCH_USES_EFI {
+        return Ok(false);
+    }
+    Path::new("/sys/firmware/efi")
+        .try_exists()
+        .map_err(Into::into)
+}
+
 #[context("Installing bootloader")]
 pub(crate) fn install_via_bootupd(
     device: &Utf8Path,
     rootfs: &Utf8Path,
     boot_uuid: &str,
+    is_alongside: bool,
 ) -> Result<()> {
     let verbose = std::env::var_os("BOOTC_BOOTLOADER_DEBUG").map(|_| "-vvvv");
-    let args = ["backend", "install"].into_iter().chain(verbose).chain([
-        "--src-root",
-        "/",
-        "--device",
-        device.as_str(),
-        rootfs.as_str(),
-    ]);
+    let using_efi = is_efi_booted()?;
+    // If we're doing an alongside install on a BIOS-booted system, don't do EFI
+    let is_bios_only = cfg!(target_arch = "x86_64") && !using_efi && is_alongside;
+    let component_args = if is_bios_only {
+        Some("--component=BIOS")
+    } else {
+        None
+    };
+    let args = ["backend", "install"]
+        .into_iter()
+        .chain(verbose)
+        .chain(component_args)
+        .chain([
+            "--src-root",
+            "/",
+            "--device",
+            device.as_str(),
+            rootfs.as_str(),
+        ]);
     Task::new_and_run("Running bootupctl to install bootloader", "bootupctl", args)?;
 
     let grub2_uuid_contents = format!("set BOOT_UUID=\"{boot_uuid}\"\n");
@@ -73,7 +97,7 @@ pub(crate) fn install_via_bootupd(
     let bootfs =
         Dir::open_ambient_dir(bootfs, cap_std::ambient_authority()).context("Opening boot")?;
 
-    if super::install::ARCH_USES_EFI {
+    if super::install::ARCH_USES_EFI && !is_bios_only {
         let efidir = bootfs.open_dir("efi").context("Opening efi")?;
         install_grub2_efi(&efidir, &grub2_uuid_contents)?;
     }

lib/src/install.rs

@@ -861,7 +861,12 @@ async fn install_to_filesystem_impl(state: &State, rootfs: &mut RootSetup) -> Re
         .get_boot_uuid()?
         .or(rootfs.rootfs_uuid.as_deref())
         .ok_or_else(|| anyhow!("No uuid for boot/root"))?;
-    crate::bootloader::install_via_bootupd(&rootfs.device, &rootfs.rootfs, boot_uuid)?;
+    crate::bootloader::install_via_bootupd(
+        &rootfs.device,
+        &rootfs.rootfs,
+        boot_uuid,
+        rootfs.is_alongside,
+    )?;
     tracing::debug!("Installed bootloader");
 
     // If Ignition is specified, enable it