Sorry for the rather long email, but I have hit a major snag in my work
with QEMU.
As part of the SATK (https://github.com/s390guy/SATK) project, I have
been working on extending bare-metal program support to QEMU by the
project.
Many bare-metal programs at some point need to share information with
the user. SCLP write events provide this vehicle and write events are
working within a bare-metal program.
However, SCLP read events, the mechanism one would expect to use to
allow a query from the user is not. The implementation makes a request
for a read event and gets the X'60F0' reason code and response class
for no available events.
That makes perfect sense, because I have not been able to actually type
any input that could turn into a read event.
Is there a configuration option required to enable communication with
the emulated SCLP console from the QEMU process console input?
This is the command by which I invoke QEMU:
/home/harold/qemu-7.2.0-rc4/install/bin/qemu-system-s390x -machine
s390-ccw-virtio -cpu max -m 3M -no-shutdown -nographic -serial
mon:stdio -kernel test9.elf
As the command line reflects, I am testing with QEMU 7.2.0 rc4.
One of the concerns I have had is that the program terminates before I
can type the input. In this regard I have tried various attempts to
get the program to "continue" by use of timer related interruptions,
specifically CPU Timer and Clock Comparator external interruptions.
(And, yes, the active PSW is enabled for external interruptions and the
subclass mask is set as needed in control register zero.)
In the case of the CPU Timer it decrements, but never below zero. It
stops at zero and does not decrement to a negative value required for a
CPU Timer external interrupt.
In the case of the Clock Comparator, it does not appear to ever compare
the actual TOD Clock to the Clock Comparator register. The TOD Clock
advances past the Clock Comparator, but no external interruption is
generated.