On aarch64, SMBIOS is only available when using UEFI, so let's make
sure that the creds test uses UEFI when available so that it can
read creds from SMBIOS when running in a virtual machine.
A fixed name is too rigid, let's give users the ability to define
custom drop-in names which at the same time also allows defining
multiple dropins per unit.
We use ~ as the separator because:
- ':' is not allowed in credential names
- '=' is used to separate credential from value in mkosi's --credential
argument.
- '-' is commonly used in filenames
- '@' already has meaning as the unit template specifier which might be
confusing when adding dropins for template units
This extends the test framework a bit, and allows adding additional
initrds to the qemu invocation, which we use here to place credentials
in the new /run/systemd/@initrd/ credentials dir which are then passed
to the host.
This imports credentials also via SMBIOS' "OEM vendor string" section,
similar to the existing import logic from fw_cfg.
Functionality-wise this is very similar to the existing fw_cfg logic,
both of which are easily settable on the qemu command line.
Pros and cons of each:
SMBIOS OEM vendor strings:
- pro: fast, because memory mapped
- pro: somewhat VMM independent, at least in theory
- pro: qemu upstream sees this as the future
- pro: no additional kernel module needed
- con: strings only, thus binary data is base64 encoded
fw_cfg:
- pro: has been supported for longer in qemu
- pro: supports binary data
- con: slow, because IO port based
- con: only qemu
- con: requires qemu_fw_cfg.ko kernel module
- con: qemu upstream sees this as legacy
Specifying the test number manually is tedious and prone to errors (as
recently proven). Since we have all the necessary data to work out the
test number, let's do it automagically.
