- Got rid of dummy proc[0]. Now proc[0] is init.
- Added initcode.S to exec /init, so that /init is
just a regular binary.
- Moved exec out of sysfile to exec.c
- Moved code dealing with fs guts (like struct inode)
from sysfile.c to fs.c. Code dealing with system call
arguments stays in sysfile.c
- Refactored directory routines in fs.c; should be simpler.
- Changed iget to return *unlocked* inode structure.
This solves the lookup-then-use race in namei
without introducing deadlocks.
It also enabled getting rid of the dummy proc[0].
shell parses arguments (very simplistic)
readme version of README (sh doesn't deal with capital characters)
printf recognizes %c
nicer output format for ls
give cpu1 a TSS and gdt for when it enters scheduler()
and a pseudo proc[] entry for each cpu
cpu0 waits for each other cpu to start up
read() for files
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.
