On 03/17/16 09:42, Gerd Hoffmann wrote: > Hi, > >>> Having a mis-use of this feature become "institutionalized" over time was >>> seen as a low/negligible risk at the time. Do we have any new reasons >>> to worry about it ? >> >> OVMF uses this feature for a few flags. They are all called >> "opt/ovmf/...". I followed the advice in "docs/specs/fw_cfg.txt" (which >> shouldn't be surprising since I seem to have reviewed every patch for >> that file): > > seabios has a few flags too, in etc/. Some of them are supported > directly by qemu (such as setting the boot menu delay).
I forgot to confirm: clearly, when some flag already exists on which we can foist, kicking and screaming, a somewhat similar interpretation in OVMF, we do that without inventing a new flag. The boot menu delay is like this. Namely, if you set "-boot menu=on,splash-time=5000", you will get a progress bar for five seconds before auto-booting the otherwise relevant boot option. The QEMU manual documents the -boot option as guest firmware-specific, and OVMF operates with that in mind -- support what it can, as closely it can. Thanks Laszlo > Others are not, > and I'd like to be able to use -fw_cfg for them for testing/debugging > (any use cases beyond that should be supported by adding a less obscure > way to set them to qemu, similar to the boot delay). > > Oh, and that'll most likely be more seabios testing than qemu testing, > so why require me build a special qemu version for that? > > On the ovmf flags: What kind of flags are there? Anything a normal > user might want to set? > > cheers, > Gerd >