Re: [PATCH] tools: Remove support for qemu-trad's battery reporting

[Jürgen Groß]

On 26.03.25 15:05, Andrew Cooper wrote:

On 25/03/2025 5:41 pm, Alejandro Vallejo wrote:

The way this undocumented feature works is via qemu-trad (who nobody
uses anymore), by intercepting 3 magic PIOs. 0x88 is one of them, and
it's probed by hvmloader as a means of detecting support for this (so,
on qemu-upstream this check always fails). If hvmloader detects the
feature, it appends an SSDT with AML inherited from some laptop ~20y
ago. QEMU then communicates with a userspace daemon (xenpmd) via an
undocumented xenstore key ("refreshbatterystatus") in order to report
battery levels.

Any chance we can make this less undocumented, even if it is a note
saying "removed now" ?

Seeing how no one uses, mantains or cares about qemu-trad anymore, rip
it all out. The hvmloader check, the SSDT generation logic and xenpmd.

Signed-off-by: Alejandro Vallejo <alejandro.vall...@cloud.com>
---
If this feature is truly wanted, it must be implemented in
qemu-upstream. Ideally in a MUCH less roundabout way. And definitely
without involving xenstore.
---
  .gitignore                      |   1 -
  tools/Makefile                  |   1 -
  tools/firmware/hvmloader/util.c |   7 -
  tools/libacpi/Makefile          |   2 +-
  tools/libacpi/build.c           |   9 -
  tools/libacpi/libacpi.h         |   2 +-
  tools/libacpi/ssdt_pm.asl       | 409 -------------------------
  tools/xenpmd/Makefile           |  30 --
  tools/xenpmd/xenpmd.c           | 525 --------------------------------
  9 files changed, 2 insertions(+), 984 deletions(-)
  delete mode 100644 tools/libacpi/ssdt_pm.asl
  delete mode 100644 tools/xenpmd/Makefile
  delete mode 100644 tools/xenpmd/xenpmd.c

I'm tempted to summarily ack this based on diffstat alone.

Juergen has expressed an interest in finally purging qemu-trad in this
release cycle, which I agree with.

If we're going to do this, then I suggest we delete qemu-trad first.
Otherwise we are technically breaking something that someone might be using.

I'm working on the patches right now.


Juergen

OpenPGP_0xB0DE9DD628BF132F.asc
Description: OpenPGP public key

OpenPGP_signature.asc
Description: OpenPGP digital signature