On Mon, Jun 08, 2026 at 10:24:28AM +0100, Peter Maydell wrote:
> On Thu, 4 Jun 2026 at 10:27, Gerd Hoffmann <[email protected]> wrote:
> >
> > On Thu, May 28, 2026 at 03:28:05PM +0100, Peter Maydell wrote:
> > > On Thu, 21 May 2026 at 12:28, Gerd Hoffmann <[email protected]> wrote:
> > > >
> > > > Also little refactoring in preparation
> > > > to avoid code duplication.
> > > >
> > > > Gerd Hoffmann (3):
> > > >   hw/nvram: add load_image_to_fw_cfg_file()
> > > >   hw/i386: switch shim loading to load_image_to_fw_cfg_file
> > > >   hw/arm: add support for shim loading
> > >
> > > Any chance of some information on what this is?
> >
> > It passes the shim binary to the efi firmware,
> > in addition to the kernel binary.
> >
> > x86 has this for a while already, this brings arm on par.
> >
> > docs update with some background below.
> >
> > take care,
> >   Gerd
> >
> > --- a/docs/system/linuxboot.rst
> > +++ b/docs/system/linuxboot.rst
> > @@ -17,6 +17,15 @@ Use ``-kernel`` to provide the Linux kernel image and 
> > ``-append`` to
> >  give the kernel command line arguments. The ``-initrd`` option can be
> >  used to provide an INITRD image.
> >
> > +The ``-shim`` option specifies the shim.efi binary.  This is needed
> > +when using direct kernel boot with UEFI secure boot enabled.  The
> > +verification chain used by linux distros requires shim.efi.  Typically
> > +shim.efi is signed by micsosoft and verified by the firmware.  The
> > +linux kernel is signed by the distro and is verified by shim.efi.  So
> > +without shim.efi in the loop secure boot verification will not work.
> > +Usually you can find shim.efi as ``EFI/BOOT/BOOT{X64,AA64}.EFI`` on
> > +distro install media.
> 
> Thanks. I'm not sure why you'd want to enable UEFI secure boot
> when you're not booting via UEFI, though.

When not booting via UEFI you can ignore that.

> Do we actually run the shim.efi code, or is it just there to
> be "verified" ?

edk2 firmware will load + run it (if present).

take care,
  Gerd


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