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server/usr/share/doc/ovmf/README.Debian
2026-01-07 20:52:11 +01:00

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The OVMF_CODE*.fd files provide UEFI firmware for a QEMU guest that is
intended to be read-only. The OVMF_VARS*.fd files provide UEFI variable
template images which are intended to be read-write, and therefore each
guest should be given its own copy. Here's an overview of each of them:
OVMF_CODE_4M.fd
Use this for booting guests in non-Secure Boot mode. While this image
technically supports Secure Boot, it does so without requiring SMM
support from QEMU, so it is less secure. Use the OVMF_VARS.fd template
with this.
OVMF_CODE_4M.ms.fd
This is a symlink to OVMF_CODE_4M.secboot.fd. It is useful in the context
of libvirt because the included JSON firmware descriptors will tell libvirt
to pair OVMF_VARS.ms.fd with it, which has Secure Boot pre-enabled.
OVMF_CODE_4M.secboot.fd
Like OVMF_CODE_4M.fd, but will abort if QEMU does not support SMM.
Use this for guests for which you may enable Secure Boot. Be aware
that the included JSON firmware descriptors associate this with
OVMF_CODE_4M.fd. Which means, if you specify this image in libvirt, you'll
get a guest that is Secure Boot-*capable*, but has Secure Boot disabled.
To enable it, you'll need to manually import PK/KEK/DB keys and activate
Secure Boot from the UEFI setup menu. If you want Secure Boot active from
the start, consider using OVMF_CODE.ms.fd instead.
OVMF_VARS_4M.fd
This is an empty variable store template, which means it has no
built-in Secure Boot keys and Secure Boot is disabled. You can use
it with any OVMF_CODE image, but keep in mind that if you want to
boot in Secure Boot mode, you will have to enable it manually.
OVMF_VARS_4M.ms.fd
This template has distribution-specific PK and KEK1 keys, and
the default Microsoft keys in KEK/DB. It also has Secure Boot
already activated. Using this with OVMF_CODE.ms.fd will boot a
guest directly in Secure Boot mode.
OVMF.fd
This is a unified image that includes the contents of both
OVMF_CODE.fd and OVMF_VARS.fd. It is provided as a convenience for
testing purposes, as it can be easily booted by QEMU using the -bios
option. It should not be used for production VMs. If VMs need to
update their variables, they need to have their own writeable copy
of this image. Making such a copy divorces the OVMF_CODE content in
those images from the code provided by the ovmf package, and they
will therefore not automatically benefit from updates made to the
ovmf package, as would be the case for VMs that use the system
OVMF_CODE.fd image and their own writeable OVMF_VARS.fd image. New
unified images are not being provided for additional variants
(secboot, etc).
OVMF.amdsev.fd
This is a stateless image that provides AMD SEV-SNP functionality,
enabling support for for SEV-secured Virtual Machine Remote Attestation.
OVMF_CODE_4M.snakeoil.fd
OVMF_VARS_4M.snakeoil.fd
This image is **for testing purposes only**. It includes an insecure
"snakeoil" key in PK, KEK & DB. The private key and cert are also
shipped in this package as well, so that testers can easily sign
binaries that will be considered valid.
PkKek-1-snakeoil.key
PkKek-1-snakeoil.pem
The private key and certificate for the snakeoil key. Use these
to sign binaries that can be verified by the key in the
OVMF_VARS.snakeoil.fd template. The password for the key is
'snakeoil'.
-- dann frazier <dannf@debian.org>, Sun, 24 Dec 2023 14:43:17 -0700