The system can finally idle without burning CPU. :^)
There are some issues with scheduling making the mouse cursor sloppy
and unresponsive that need to be dealt with.
When you open /dev/ptmx, you get a file descriptor pointing to one of the
available MasterPTY's. If none are available, you get an EBUSY.
This makes it possible to open multiple (up to 4) Terminals. :^)
To support this, I also added a CharacterDevice::open() that gets control
when VFS is opening a CharacterDevice. This is useful when we want to return
a custom FileDescriptor like we do here.
Userspace programs can now open /dev/gui_events and read a stream of GUI_Event
structs one at a time.
I was stuck on a stupid problem where we'd reenter Scheduler::yield() due to
having one of the has_data_available_for_reading() implementations using locks.
Process page directories can now actually be freed. This could definitely
be implemented in a nicer, less wasteful way, but this works for now.
The spawn stress test can now run for a lot longer but eventually dies
due to kmalloc running out of memory.
Also use a simple array of { dword, const char* } for the KSyms and put the
whole shebang in kmalloc_eternal() memory. This was a fugly source of
kmalloc perma-frag.
Pass the file name in a stack-allocated buffer instead of using an AK::String
when iterating directories. This dramatically reduces the amount of cycles
spent traversing the filesystem.
- Process::exec() needs to restore the original paging scope when called
on a non-current process.
- Add missing InterruptDisabler guards around g_processes access.
- Only flush the TLB when modifying the active page tables.
sys$fork() now clones all writable regions with per-page COW bits.
The pages are then mapped read-only and we handle a PF by COWing the pages.
This is quite delightful. Obviously there's lots of work to do still,
and it needs better data structures, but the general concept works.
We no longer disable interrupts around the whole affair.
Since MM manages per-process data structures, this works quite smoothly now.
Only procfs had to be tweaked with an InterruptDisabler.
