Commit graph

8 commits

Author SHA1 Message Date
rsc
ad12b487b5 changes since two days ago:
drop , address=0xf0000 from romimage line.
newer bochs has a 128k bios that it loads elsewhere.
so let bochs decide where the romimage goes.

change cpu quantum to 1 (default is 5, max is 16)
in an attempt to provoke more races.  only provokes
them slightly more frequently, may not be worth
the slowdown.
2007-09-27 11:27:04 +00:00
rsc
b30ab3f5af use standard bios location 2007-09-27 05:14:25 +00:00
rsc
666f58c711 believe it or not, this was working
the macro expansion of "char *cp;" turned into
char *(curproc[cpu()]);  which declares a dynamically
sized array of char* called curproc.

so then &cp == &(curproc[cpu()]) was actually a
stack variable as "expected".  it was one past the
end of the array, but the implicit alloca allocated
more than was necessary.

do not tell me that making cp a #define was a bad idea.
there are worse problems to fix.  more on that later.
2007-09-27 05:13:10 +00:00
rtm
54a4b00346 update 2006-07-26 10:17:39 +00:00
rsc
65bd8e139a New scheduler.
Removed cli and sti stack in favor of tracking
number of locks held on each CPU and explicit
conditionals in spinlock.c.
2006-07-16 01:15:28 +00:00
rsc
5ce9751cab Changes to allow use of native x86 ELF compilers, which on my
Linux 2.4 box using gcc 3.4.6 don't seem to follow the same
conventions as the i386-jos-elf-gcc compilers.
Can run make 'TOOLPREFIX=' or edit the Makefile.

curproc[cpu()] can now be NULL, indicating that no proc is running.
This seemed safer to me than having curproc[0] and curproc[1]
both pointing at proc[0] potentially.

The old implementation of swtch depended on the stack frame layout
used inside swtch being okay to return from on the other stack
(exactly the V6 you are not expected to understand this).
It also could be called in two contexts: at boot time, to schedule
the very first process, and later, on behalf of a process, to sleep
or schedule some other process.

I split this into two functions: scheduler and swtch.

The scheduler is now a separate never-returning function, invoked
by each cpu once set up.  The scheduler looks like:

	scheduler() {
		setjmp(cpu.context);

		pick proc to schedule
		blah blah blah

		longjmp(proc.context)
	}

The new swtch is intended to be called only when curproc[cpu()] is not NULL,
that is, only on behalf of a user proc.  It does:

	swtch() {
		if(setjmp(proc.context) == 0)
			longjmp(cpu.context)
	}

to save the current proc context and then jump over to the scheduler,
running on the cpu stack.

Similarly the system call stubs are now in assembly in usys.S to avoid
needing to know the details of stack frame layout used by the compiler.

Also various changes in the debugging prints.
2006-07-11 01:07:40 +00:00
rtm
0a70d042d0 more or less take traps/interrupts 2006-06-13 15:50:06 +00:00
rtm
70a895f63c xx 2006-06-12 15:27:13 +00:00