[edk2-devel] [PATCH 00/12] Introduce Bootlog DEBUG() output

[Gerd Hoffmann]

  Hi,

> > Hmm. Maybe it's time to tackle the log performance problem for virtual
> > machines? Create a debug log device with DMA support, so we don't need
> > a vmexit for every single character we want log?
> 
> Of course, that doesn't work for native systems.

Yep.  Maybe we should have both ;)

> > How does that relate to coreboot? coreboot has logging-to-memory too.
> > Not sure what the state is, there have been discussions on the coreboot
> > list about changing that from a pure text log to something structed with
> > timestamps a while back. Don't know whenever this did actually happen.
> > 
> > So, when adding logging-to-memory to edk2 it surely make sense to
> > coordinate that with coreboot, so we'll have both coreboot and edk2 logs
> > there in case edk2 runs as coreboot payload.
> 
> I'm working on getting a SerialPortLib that logs to CBMEM merged. It's on the list at the moment.

> Some comments on DebugLibBootlog:

> - SMM-phase logging can be implemented, but I'm not convinced that sharing DXE's buffer is entirely safe. Using SMM communicate could be safer, but would be more complicated. I stopped working on it when the return-on-investment was too low.

DebugLibBootlog supports multiple buffers.  So we could have one for
coreboot, one for edk2 pei/dxe, one for edk2 smm, one for shim, one for
grub, ...

take care,
  Gerd



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