Before I assumed that bootloaders loaded the kernel at physical address
0, but this patch kinda allows loading to different addresses. This
still doesn't fully work as kernel bootstrap paging relies on kernel
being loaded at 0
This cleans up the kernel executable as bootloaders don't have to
load AP init code straight to 0xF000, but it will be moved there once
kernel is doing the AP initialization.
This makes scheduler preemption much cleaner as bsb does not have to
send smp messages to notify other processes about timer interrupt.
Also PIT percision is now "full" 0.8 us instead of 1 ms that I was using
before.
Change Semaphore -> ThreadBlocker
This was not a semaphore, I just named it one because I didn't know
what semaphore was. I have meant to change this sooner, but it was in
no way urgent :D
Implement SMP events. Processors can now be sent SMP events through
IPIs. SMP events can be sent either to a single processor or broadcasted
to every processor.
PageTable::{map_page,map_range,unmap_page,unmap_range}() now send SMP
event to invalidate TLB caches for the changed pages.
Scheduler no longer uses a global run queue. Each processor has its own
scheduler that keeps track of the load on the processor. Once every
second schedulers do load balancing. Schedulers have no access to other
processors' schedulers, they just see approximate loads. If scheduler
decides that it has too much load, it will send a thread to another
processor through a SMP event.
Schedulers are currently run using the timer interrupt on BSB. This
should be not the case, and each processor should use its LAPIC timer
for interrupts. There is no reason to broadcast SMP event to all
processors when BSB gets timer interrupt.
Old scheduler only achieved 20% idle load on qemu. That was probably a
very inefficient implementation. This new scheduler seems to average
around 1% idle load. This is much closer to what I would expect. On my
own laptop idle load seems to be only around 0.5% on each processor.
This implements only parsing for AML in qemu. InvokeMethods are not
parsed since number of arguments to Methods is not yet known.
Parsing AML uses multiple kilobytes of stack space, so I increased
boot stack size by a lot :D
I am not sure where my own AML is going, but this is good start if
I decide to implement full ACPI on my own.
This code is very much just ugly macro expansion.
Qemu has 2 DefPackage elements that I am not able to parse. Package
data ends while there should be still multiple elements.
Current context saving was very hacky and dependant on compiler
behaviour that was not consistent. Now we always use iret for
context saving. This makes everything more clean.
This allows us to allocate processor stacks, and other per processor
structures dynamically in runtime. Giving processor stack to
ap_trampoline feels super hacky, but it works for now.
Signal handling code was way too complex. Now everything is
simplified and there is no need for ThreadBlockers.
Only complication that this patch includes is that blocking syscalls
have to manually be made interruptable by signal. There might be some
clever solution to combat this is make this happen automatically.
Bananymous