- Only the topmost parent prints pass messages. Any failed child can print fail message.
- Added testing of 16 forked threads doing file create/read/write/close and
16 forked x 4 cloned = 64 threads spawning/exiting
Added setting of utcb address to l4_thread_control.
This is going to be moved to exchange_registers() since we need to pass
both the utcb physical and virtual address and exregs fits such context
modification better than thread_control.
- Now libl4 has no references to utcb page or shmat etc.
- Pager does not deal with special case utcb page allocation.
It instead allocates a shared page from shm memory pool.
- All tasks working to original standard.
Next:
- Add per-thread utcb allocation from the kernel
- Add larger register file for standard ipc
- Add long ipc (up to 1Kb)
Increased inode block pointers to 40. The current maximum allowed (and checked).
Updates to file size after every file write ensures subsequent writes can
correctly operate using updated file size information (i.e. not try to add
more pages that are already present). We cannot do this inside write() because
directory writes rely on byte-granularity updates on file buffers, whereas
file updates are by page-granularity (currently).
It turned out we used one version of kmalloc for malloc() and another for kfree()!
Now fixed.
Added parent-child relationship to tasks. Need to polish handling CLONE_PARENT and THREAD.
- Updated sleeping paths such that a task is atomically put into
a runqueue and made RUNNABLE, or removed from a runqueue and made SLEEPING.
- Modified vma dropping sources to handle both copy_on_write() and exit() cases
in a common function.
- Added the first infrastructure to have a pager to suspend a task and wait for
suspend completion from the scheduler.
fs0 used to receive open() requests and notify pager about them via a syscall ipc.
This caused deadlocks because normally request flow is mm0 -> fs0 on all other calls.
The solution was to have mm0 ask and validate file descriptors from fs0 on the first
request instance that involved that file descriptor. By this method we delay the
validation of the fd until its first use, and avoid deadlock. It also fits well with
the lazy request handling design philosophy.
- Added automatic utcb map/prefaulting of forked tasks for fs0
so that it does not need to explicitly request those tasks from mm0.
Eliminating fs0 requests to mm0 reduce deadlock possibilities.
- Replaced kmalloc with a public malloc implementation because of a bug in kmalloc.
- Fixed a kfree bug. default_release_pages was trying to free page_array pages.
serving mm0, if it page faults, system deadlocks because mm0 is waiting to be served by vfs.
FIX: To fix this, mm0 will need to fork itself and keep a separate thread solely for
page fault handling.
close() needs to flush dirty buffers.
pager needs to have read/write support properly implemented.
open() needs to record mode and access times.
The need for access times means we need rtc and time implementation.
Also need to add stat() access() etc.
Bahadir Balban