Comment 3 for bug 1753558

The QEMU maintainers consider the "fw_cfg" feature to be only intended for QEMU to communicate with the firmware. While some projects have indeed used fw_cfg for general purpose data passthrough, this is discouraged by QEMU maintainers. There are a fairly small, limited number of data slots in fw_cfg, and QEMU needs to be able to use these precious free slots for its own tasks in future.

I implemented support for the "OEM strings" feature in SMBIOS for QEMU so that applications would have a mechanism which is functionally on a par with fw_cfg, and thus enable apps to avoid the precious fw_cfg slots

SMBIOS is available for x86, x64 and aarch64 targets in QEMU, which is equivalent to fw_cfg coverage IIRC.