on 386 kernel, each processor has its own pdb where the primary
pdb for kernel mappings is on cpu0 and other cpu's lazily pull
pdb entries from cpu0 when they fault in vmapsync().
so we have to edit the table tables in the pdb of cpu0 and not
the current processor.
on some modern machines like the x250, the bios arranges the mtrr's
and the framebuffer membar in a way that doesnt allow us to mark
the framebuffer pages as write combining, leading to slow graphics.
since the pentium III, the processor interprets the page table bit
combinations of the WT, CD and bit7 bits as an index into the
page attribute table (PAT).
to not change the semantics of the WT and CD bits, we preserve
the bit patterns 0-3 and use the last entry 7 for write combining.
(done in mmuinit() for each core).
the new patwc() function takes virtual address range and changes
the page table marking the range as write combining. no attempt
is made on invalidating tlb's. doesnt matter in our case as the
following mtrr() call in screen.c does it for us.
the assumption of only one producer ((abs)moustratrack()) is not true
for external mouse events from /dev/mousein, so protect the mouse state
and queue with ilock().
get rid of mousecreate(), just use devcreate().
reset cursor when all instances of /dev/mouse and /dev/cursor got closed,
instead of also considering /dev/mousectl. the reason is that kbdfs keeps
the mousectl file open. so exiting a program that has the cursor changed
will properly reset the cursor to arrow.
don't access user buffer while holding cursor spinlock! the memory access
can fault. theres also no lock needed there, we'r just copying *from* the
cursor memory.
fix use of strtol(), p will always be set, check for end of string.
keep pointer coordinates onscreen (off by one).
make lastms() function to get the last millisecond delta of last
call for resynchronization.
fix msg[3] buffer overflow in m5mouseputc().
get rid of mouseshifted logic, it is not used.
theres a bug is in sclose() where it doesnt check if wp is beyond
the buffer. also wp was not updated after realloc().
bug was reported by porlock on 9fans:
Plan 9's implementation of the standard C functions snprintf and
vsnprintf have a buffer overrun bug.
If the buffer length equals the output length (without the terminating
null), then one too many characters is written to the buffer.
For example,
snprintf(buf, 4, "ABCD");
will write 5 characters to buf.
remove bl2mem(), it is broken. a fault while copying to memory
yields a partially freed block list. it can be simply replaced
by readblist() and freeblist(), which we also use for qcopy()
now.
remove mem2bl(), and handle putting back remainer from a short
read internally (splitblock()) avoiding the releasing and re-
acquiering of the ilock.
always attempt to free blocks outside of the ilock.
have qaddlist() return the number of bytes enqueued, which
avoids walking the block list twice.
