On Tue, 25 Apr 2023 at 11:34, Daniel Bertalan <d...@danielbertalan.dev> wrote: > > 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.
Are there any particularly interesting bits of guest software that try to read this property ? I added a brief comment to the code about the no-NUL-terminator and short-buffer handling so that future readers of the code don't have to refer back to the commit message: + /* + * We follow the firmware behaviour: no NUL terminator is + * written to the buffer, and if the buffer is too short + * we report the required length in the response header + * and copy nothing to the buffer. + */ and have applied this to target-arm.next; thanks. -- PMM
