kmi - ACTIVE - Kernel with migrating threads as IPC

Age	Commit message (Collapse)	Author
2023-04-30	rename to kmi	Kimplul

2023-01-26	add req_page syscall	Kimplul

2023-01-16	initialize variable to zero	Kimplul
	+ Silences possible warning
2023-01-16	make process ids signed	Kimplul
	+ Unlikely to ever run into billions of threads, and this keeps in line with stuff like Linux. Also allows C to relatively painlessly implement hashmaps of pids, if neccessary.
2022-12-02	remove MR_SHARED	Kimplul
	+ The new shared memory plan doesn't need it.
2022-12-02	initial shared memory working	Kimplul

2022-12-01	start looking into memory handling	Kimplul
	+ Now 10M alloc/frees succeed, which totals more memory than the virtual machine has, so no too obvious leaks are occuring. For future debugging speed, changed 10M to 1M. + Also quick fix to rpcs, stacks are now assigned. Not entirely sure why they worked before this, but good that I found it.
2022-11-21	fix llvm	Kimplul

2022-11-21	make syscall handlers void	Kimplul

2022-11-21	fix formatting	Kimplul

2022-11-21	possible optimisations	Kimplul

2022-11-13	improve tcb list handling	Kimplul

2022-11-13	give symbolic name to rpc stack ratio	Kimplul

2022-11-13	NDEBUG with release mode	Kimplul
	+ Might be a good idea to add some command line variable as debugging release mode can be useful for performance profiling (until I start writing proper serial userspace drivers)
2022-11-13	outline rpc stack handling	Kimplul

2022-11-13	improve documentation on new features	Kimplul

2022-11-13	~1.3M ipc requests	Kimplul
	+ The secret is using gravestones. I'll have to write up full documentation for the feature but essentially riscv lets us encode whatever we want into page table entries, as long as they're not active. We use this to encode highest user address that is not a zero, in that all entries in the top level are either active or gravestones. When an active entry is removed, it is either a gravestone (if there are other active entries above it) or it starts a cascade of removing entries that have been previously removed Slight runtime overhead to page mapping, pretty major advantage in rpc calls. Feature will need to be tested more thorougly, and the init program is sort of a best scenario with just one top level userspace page table entry active at a time, leading to incredibly fast context switches. Current implementation limits a process' max virtual memory to 248 GiB (in Sv39), but I don't think the missing 8 GiB is that big of a deal.
2022-11-13	~700k ipc requests	Kimplul
	+ Eliminated need for save/load_regs, now the register save area is behind a pointer which _slightly_ increases overall syscall delay, but speeds up ipc requests by a fair bit.
2022-11-13	give uvmem_map more fitting name	Kimplul
	+ It really only works with Sv39, I suppose similar structures should be added for Sv4} etc. if I ever get around to it.
2022-11-13	write init more sensibly	Kimplul
	+ Both easier to look at and now the userspace doesn't play as big of a role in the 'benchmarking' with optimizations turned on.
2022-11-12	release mode, ~600k requests	Kimplul

2022-11-12	make 'performance' results more accurate in qemu	Kimplul

2022-11-12	slight optimization	Kimplul

2022-11-12	initial rpc implementations	Kimplul

2022-11-11	less buggy fork	Kimplul
	+ Not strictly done yet, but we can swap between two processes :D
2022-11-10	initial implementation of process copying	Kimplul
	+ Not actually working (at least fully), need to continue debugging when I have time.
2022-11-09	silence ubsan and docs warnings	Kimplul

2022-11-09	update docs	Kimplul

2022-11-09	add basic IPI structure	Kimplul

2022-10-29	fix warning in mem.c	Kimplul

2022-10-29	rewrite pmem	Kimplul

2022-10-22	start outlining ipc	Kimplul

2022-10-22	create impl and CAP_PROC checking	Kimplul

2022-10-22	initial high level fork imp	Kimplul

2022-10-21	beautification	Kimplul

2022-10-21	initial implementation of swap	Kimplul
	+ Slightly unsure if it should be a syscall, or if assign would be enough. Also, which thread should run in a fork/spawn? For now, old thread, though this might increase latency. Or add swap flag to these calls?
2022-10-21	initial spawn implementation	Kimplul

2022-10-21	slight optimisation to cur_tcb on riscv	Kimplul

2022-10-14	add spawn syscall	Kimplul
	+ Prefer over unixy fork/exec for speed since I don't want to support cow. Shell redirection should be done with env server and cooperating libc.
2022-10-14	remove references to cow	Kimplul
	+ Skip cow for now, maybe implement later but try to keep things simple.
2022-09-23	add notify_state to tcb	Kimplul

2022-09-23	remove user data from sys_ipc_notify	Kimplul
	+ Multiple notify signals at the same time, or queued ones waiting for ipc_req/fwd to finish would require a notify stack of some kind, which is maybe too complex for my liking. Not impossible by any means, but I want to keep things simple. Let's say a client wants the server to do some async operation. First, the client calls ipc_req to inform the server that it would like the operation to be done. The server sets this task in some work queue or whatever, and returns to the client as quickly as possible. Later on, when the task is finished, the server does a ipc_req to the client, with data about what was just finished. The client is responsible for noting this data down somewhere, either reacting to the operation directly in the callback, or calling ipc_notify to the thread that requested the operation. Other possible notifications at the same time should be handled at the same time, whichever way the client wants to handle them. Note that ipc_notify triggers only when the thread it targets is in its base state, i.e. not doing an ipc_req. This makes things a bit easier.
2022-09-22	add assign syscall skeleton	Kimplul

2022-09-20	add notify syscall skeleton	Kimplul
	+ Now to actually start implementing shit. :)
2022-09-20	add capability subsystem and syscalls	Kimplul

2022-09-15	change syscalls to take 5 params and return 6	Kimplul
	+ In total, a syscall is built up of 6 values, with the first being the syscall number. Symmetrically, the first value is now a status and the following five values return "values". This allows us to cram in more info into the ipc_* functions. The performance difference is absolutely minimal, at least from my testing in qemu.
2022-09-15	add SYS_TICKS	Kimplul

2022-09-14	add putch syscall for easier userspace debugging	Kimplul
	+ Note that it is NOT intended for end user usage, just for debugging.
2022-09-14	add canary to kernel stack	Kimplul

2022-09-14	riscv32 boots and advances as far as riscv64	Kimplul