uptime() sys call for benchmarking
increase PHYSTOP

usys.S: put before init.c, STUB -> SYSCALL

Replace yield system call with sleep.

Add yield system call, for zombie test program (bad idea?).

standardize various * conventions

spacing fixes: no tabs, 2-space indents (for rtm)

i/o redirection in sh
better parsing of sh commands (copied from jos sh)
cat: read from 1 if no args
sbrk system call, but untested
getpid system call
moved locks in keyboard intr, but why do we get

i/o redirection in sh
better parsing of sh commands (copied from jos sh)
cat: read from 1 if no args
sbrk system call, but untested
getpid system call
moved locks in keyboard intr, but why do we get intr w. null characters from keyboard?

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removed block system call
renumber system calls (run gmake clean!)
skeleton for dup system call

chdir
cd in shell
nits in mkdir, ls, etc.

start on mkdir
stat

link()

fix getblk to actually lock the block
no more cons_put system calls
usertests tests two processes writing files

fstat
primitive ls

printf
convert userfs to use printf
bfree
ifree
writei
start on unlink

mknod,ialloc,iupdate

open()

primitive exec

Add user.h for prototypes.
Add cons_puts for cleaner output.

no more recursive locks
wakeup1() assumes you hold proc_table_lock
sleep(chan, lock) provides atomic sleep-and-release to wait for condition
ugly code in swtch/scheduler to implement new sleep
fix lo

no more recursive locks
wakeup1() assumes you hold proc_table_lock
sleep(chan, lock) provides atomic sleep-and-release to wait for condition
ugly code in swtch/scheduler to implement new sleep
fix lots of bugs in pipes, wait, and exit
fix bugs if timer interrupt goes off in schedule()
console locks per line, not per byte

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pre-empt both user and kernel, in clock interrupt
usertest.c tests pre-emption
kill()

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

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.

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