Commit graph

8 commits

Author SHA1 Message Date
rtm
b548df152b pre-empt both user and kernel, in clock interrupt
usertest.c tests pre-emption
kill()
2006-07-11 17:39:45 +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
c41f1de5d4 file descriptors
pipes
2006-06-27 14:35:53 +00:00
rtm
bf49aedbed send console output to parallel port 2006-06-22 15:51:57 +00:00
rtm
a4c03dea09 primitive fork and exit system calls 2006-06-15 16:02:20 +00:00
rtm
cb83c71628 fix some trap bugs 2006-06-13 22:08:20 +00:00
rtm
0a70d042d0 more or less take traps/interrupts 2006-06-13 15:50:06 +00:00
rtm
55e95b16db import 2006-06-12 15:22:12 +00:00