8b58e81077
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?
141 lines
4.5 KiB
Plaintext
141 lines
4.5 KiB
Plaintext
bochs 2.2.6:
|
|
./configure --enable-smp --enable-disasm --enable-debugger --enable-all-optimizations --enable-4meg-pages --enable-global-pages --enable-pae --disable-reset-on-triple-fault
|
|
bochs CVS after 2.2.6:
|
|
./configure --enable-smp --enable-disasm --enable-debugger --enable-all-optimizations --enable-4meg-pages --enable-global-pages --enable-pae
|
|
|
|
bootmain.c doesn't work right if the ELF sections aren't
|
|
sector-aligned. so you can't use ld -N. and the sections may also need
|
|
to be non-zero length, only really matters for tiny "kernels".
|
|
|
|
kernel loaded at 1 megabyte. stack same place that bootasm.S left it.
|
|
|
|
kinit() should find real mem size
|
|
and rescue useable memory below 1 meg
|
|
|
|
no paging, no use of page table hardware, just segments
|
|
|
|
no user area: no magic kernel stack mapping
|
|
so no copying of kernel stack during fork
|
|
though there is a kernel stack page for each process
|
|
|
|
no kernel malloc(), just kalloc() for user core
|
|
|
|
user pointers aren't valid in the kernel
|
|
|
|
are interrupts turned on in the kernel? yes.
|
|
|
|
pass curproc explicitly, or implicit from cpu #?
|
|
e.g. argument to newproc()?
|
|
hmm, you need a global curproc[cpu] for trap() &c
|
|
|
|
no stack expansion
|
|
|
|
test running out of memory, process slots
|
|
|
|
we can't really use a separate stack segment, since stack addresses
|
|
need to work correctly as ordinary pointers. the same may be true of
|
|
data vs text. how can we have a gap between data and stack, so that
|
|
both can grow, without committing 4GB of physical memory? does this
|
|
mean we need paging?
|
|
|
|
perhaps have fixed-size stack, put it in the data segment?
|
|
|
|
oops, if kernel stack is in contiguous user phys mem, then moving
|
|
users' memory (e.g. to expand it) will wreck any pointers into the
|
|
kernel stack.
|
|
|
|
do we need to set fs and gs? so user processes can't abuse them?
|
|
|
|
setupsegs() may modify current segment table, is that legal?
|
|
|
|
trap() ought to lgdt on return, since currently only done in swtch()
|
|
|
|
protect hardware interrupt vectors from user INT instructions?
|
|
|
|
test out-of-fd cases for creating pipe.
|
|
test pipe reader closes then write
|
|
test two readers, two writers.
|
|
test children being inherited by grandparent &c
|
|
|
|
some sleep()s should be interruptible by kill()
|
|
|
|
locks
|
|
init_lock
|
|
sequences CPU startup
|
|
proc_table_lock
|
|
also protects next_pid
|
|
per-fd lock *just* protects count read-modify-write
|
|
also maybe freeness?
|
|
memory allocator
|
|
printf
|
|
|
|
in general, the table locks protect both free-ness and
|
|
public variables of table elements
|
|
in many cases you can use table elements w/o a lock
|
|
e.g. if you are the process, or you are using an fd
|
|
|
|
lock order
|
|
per-pipe lock
|
|
proc_table_lock fd_table_lock kalloc_lock
|
|
console_lock
|
|
|
|
do you have to be holding the mutex in order to call wakeup()? yes
|
|
|
|
device interrupts don't clear FL_IF
|
|
so a recursive timer interrupt is possible
|
|
|
|
what does inode->busy mean?
|
|
might be held across disk reads
|
|
no-one is allowed to do anything to the inode
|
|
protected by inode_table_lock
|
|
inode->count counts in-memory pointers to the struct
|
|
prevents inode[] element from being re-used
|
|
protected by inode_table_lock
|
|
|
|
blocks and inodes have ad-hoc sleep-locks
|
|
provide a single mechanism?
|
|
|
|
test 14-character file names
|
|
and file arguments longer than 14
|
|
|
|
kalloc() can return 0; do callers handle this right?
|
|
|
|
OH! recursive interrupts will use up any amount of cpu[].stack!
|
|
underflow and wrecks *previous* cpu's struct
|
|
|
|
disk scheduling
|
|
mkdir
|
|
sh arguments
|
|
sh redirection
|
|
indirect blocks
|
|
is there a create/create race for same file name?
|
|
resulting in two entries w/ same name in directory?
|
|
why does shell often ignore first line of input?
|
|
|
|
test: one process unlinks a file while another links to it
|
|
test: one process opens a file while another deletes it
|
|
test: mkdir. deadlock d/.. vs ../d
|
|
|
|
make proc[0] runnable
|
|
cpu early tss and gdt
|
|
how do we get cpu0 scheduler() to use mpstack, not proc[0].kstack?
|
|
when iget() first sleeps, where does it longjmp to?
|
|
maybe set up proc[0] to be runnable, with entry proc0main(), then
|
|
have main() call scheduler()?
|
|
perhaps so proc[0] uses right kstack?
|
|
and scheduler() uses mpstack?
|
|
ltr sets the busy bit in the TSS, faults if already set
|
|
so gdt and TSS per cpu?
|
|
we don't want to be using some random process's gdt when it changes it.
|
|
maybe get rid of per-proc gdt and ts
|
|
one per cpu
|
|
refresh it when needed
|
|
setupsegs(proc *)
|
|
|
|
why do we get 0 characters from keyboard?
|
|
are the locks in the right place in keyboardintr?
|
|
|
|
sh: support pipes? leave it for the class?
|
|
sh: dynamic memory allocation?
|
|
sh: should sh support ; () & --- need malloc
|
|
sh: stop stdin on ctrl-d (for cat > y) |