the 6c compiler reserves R14 and R15 for extern register variables,
which is used by the kernel to hold the m and up pointers. until
now, the meaning of R14 and R15 was undefined for userspace and
extern register would not work as the kernel trashes R14 and R15
on syscalls. with this change, user extern registers R14 and R15
are zeroed on exec and otherwise preserved across syscalls. so
userspace *could* use them for per process variables like the
kernel does.
use Ureg.bp (RARG) for syscall number instead of Ureg.ax. this is
less confusing and mirrors the amd64 calling convention.
addpage() should not be called with the display locked as it
calls showpage1() which sleeps when there are too many
processes active.
the bug was triggered by plumbing to trigger the addpage().
dont kill the calling process when demand load fails if fixfault()
is called from devproc. this happens when you delete the binary
of a running process and try to debug the process accessing uncached
pages thru /proc/$pid/mem file.
fixes to procctlmemio():
- fix missed unlock as txt2data() can error
- make sure the segment isnt freed by taking a reference (under p->seglock)
- access the page with segment locked (see comment)
- get rid of the segment stealer lock
other stuff:
- move txt2data() and data2txt() to segment.c
- add procpagecount() function
- make return type mcounseg() to ulong
handle reads and writes with 9pqueue(2) so they can
be flushed and wont hang the filesystem. this also
lets us get rid of the timeouts.
ftdi is still full of braindamage that should be
rewritten, but i dont have a device to test.
instead of naming devices by ther dynamically assigned device address,
we hash device uniqueue fields from the device descriptor and produce
a 5 digit hex string that will identify the device across machines.
when there is a collision (less than 1% chance with 100 devices),
usbd will append the device address to the name to make it uniqueue
for this machine.
the hname is passed to drivers in the devid argument, which now has
the form addr:hname, where the colon and hname can be omited (for backwards
compatibility).
when the new behaviour isnt desired, nousbhname= environment variable
can be defined giving the old behaviour.
