fbos/usr/src/init.S, branch mainA RISC-V operating system devoted to running fizz/buzz processes.
https://git.mssola.com/os/fbos/atom?h=main2024-11-25T22:02:51Zusr: Simplify init.S2024-11-25T22:02:51ZMiquel Sabaté Solàmikisabate@gmail.com2024-11-25T22:02:51Zurn:sha1:30d6ab8c6b40b2897fa3f49cce0302cc6c3a66e6
There appears to be no reasonable way to call 'wfi' from user space and
making kernel space look the other way. Moreover, it also looks like
clearing TW is not working either. Hence, we will have to implement
'idle' entirely from kernel space and be reasonable about it.
Signed-off-by: Miquel Sabaté Solà <mikisabate@gmail.com>
Simplify scheduling by introducing an init process2024-11-24T21:22:48ZMiquel Sabaté Solàmikisabate@gmail.com2024-11-24T21:07:51Zurn:sha1:192208770d3866838a450462dd4b1fc8e2b5c91a
Scheduling is easier if there is an init process which does nothing.
This way we don't have to perform hacks in order to idle in S privilege
mode while touching special registers in weird ways.
For now this process is kind of costly since 'wfi' is not accepted in
this context, but this can be further tuned down in the future by
setting TW=1 on 'mstatus', or by handling the exception and allowing it
if it comes from the proper process.
All of that being said, there is still work to be done as things fail
when optimitzations are on.
Signed-off-by: Miquel Sabaté Solà <mikisabate@gmail.com>