Re: [pbs-devel] [PATCH v2 proxmox 1/3] sys: add function to get boot_mode

[Lukas Wagner <l.wagner@proxmox.com>]

On 11/24/23 13:02, Gabriel Goller wrote:
> Helper that returns the current boot_mode. Either EFI, BIOS, or EFI
> (Secure Boot).
> Detection works the same as in pve, we use `/sys/firmware/efi` and
> the `efivars/SecureBoot-xxx..` file.
> 
> Signed-off-by: Gabriel Goller <g.goller@proxmox.com>
> ---
>   proxmox-sys/src/boot_mode.rs | 47 ++++++++++++++++++++++++++++++++++++
>   proxmox-sys/src/lib.rs       |  1 +
>   2 files changed, 48 insertions(+)
>   create mode 100644 proxmox-sys/src/boot_mode.rs
> 
> diff --git a/proxmox-sys/src/boot_mode.rs b/proxmox-sys/src/boot_mode.rs
> new file mode 100644
> index 0000000..570af8e
> --- /dev/null
> +++ b/proxmox-sys/src/boot_mode.rs
> @@ -0,0 +1,47 @@
> +use std::{io::Read, sync::Mutex};
> +
> +/// The possible BootModes
> +#[derive(Clone, Copy)]
> +pub enum BootModeInformation {
> +    /// The BootMode is EFI/UEFI
> +    Efi,
> +    /// The BootMode is EFI/UEFI with Secure Boot enabled
> +    EfiSecureBoot,
> +    /// The BootMode is Legacy BIOS
> +    Bios,
> +}
> +
> +// Returns the current bootmode (BIOS, EFI, or EFI(Secure Boot))
> +pub fn boot_mode() -> BootModeInformation {
> +    lazy_static::lazy_static!(
> +        static ref BOOT_MODE: Mutex<Option<BootModeInformation>> = Mutex::new(None);
> +    );
> +
> +    let mut last = BOOT_MODE.lock().unwrap();
> +    let value = last.or_else(|| {
> +        if std::path::Path::new("/sys/firmware/efi").exists() {
> +            // Check if SecureBoot is enabled
> +            // Attention: this file is not seekable!
> +            let efivar = std::fs::File::open(
> +                "/sys/firmware/efi/efivars/SecureBoot-8be4df61-93ca-11d2-aa0d-00e098032b8c",
> +            );

Maybe add some comment what this magic EFI variable is, e.g. with a link 
to a spec?

-- 
- Lukas