tree d151200340eb288858c655ffd0a573ba9ce1e88c
parent 471896381ae895b1c4c2afe1eff2ce13d85e6c2c
author Daniel Bertalan <dani@danielbertalan.dev> 1682418871 +0000
committer Peter Maydell <peter.maydell@linaro.org> 1683038860 +0100

hw/arm/bcm2835_property: Implement "get command line" message

This query copies the kernel command line into the message buffer. It
was previously stubbed out to return empty, this commit makes it reflect
the arguments specified with `-append`.

I observed the following peculiarities on my Pi 3B+:
- If the buffer is shorter than the string, the response header gives
  the full length, but no data is actually copied.
- No NUL terminator is added: even if the buffer is long enough to fit
  one, the buffer's original contents are preserved past the string's
  end.
- The VC firmware adds the following extra parameters beside the
  user-supplied ones (via /boot/cmdline.txt): `video`, `vc_mem.mem_base`
  and `vc_mem.mem_size`. This is currently not implemented in qemu.

Signed-off-by: Daniel Bertalan <dani@danielbertalan.dev>
Message-id: 20230425103250.56653-1-dani@danielbertalan.dev
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
[PMM: added comment about NUL and short-buffer behaviour]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>