For character device i/o, FS does a so-called 'magic' grant to let the
driver copy from or to user space. As this is done in FS address space,
the driver is told to do this in FS address space. The redirection to
the right user process then happens at copy-time in the kernel, using the
FS grant table. This also happens for DEV_READ and DEV_WRITE on block
devices.
For other block device i/o, which happens from/to FS buffers, FS does
a 'direct' grant to its own address space for the driver.
After the i/o returns, this access has to be K-I-L-L-E-D, revoked.
Sometimes this is after a SUSPEND and DEV_REVIVE, in which case the
revoking happens in pipe.c.
This conversion happens in safe_io_conversion() in device.c, called
by dev_io and dev_bio.
FS has to pre-allocate its own space for these grant tables. This happens
in main.c.
library to the memory driver. Always put output from within TTY directly on
the console. Removed second include of driver.h from tty.c. Made tty_inrepcode
bigger. First step to move PM and FS calls that are not regular (API)
system calls out of callnr.h (renumbered them, and removed them from the
table.c files). Imported the Minix-vmd uname implementation. This provides
a more stable ABI than the current implementation. Added a bit of security
checking. Unfortunately not nearly enough to get a secure system. Fixed a
bug related to the sizes of the programs in the image (in PM patch_mem_chunks).
instead of keeping a running total of enqueued processes
(because somehow the load average was broken)
. added SI_KPROC_TAB to get a copy of kernel process table from PM, for
a top implementation
. fixed arg to sys_nice() to make it an endpoint, not a slot number
. loops checked for PID_FREE
. exit broken down in exit and cleanup functions; when reboot happens,
cleanup is done but not exit (as processes have not actually exited),
this keeps drivers working
. fixed a few uninitialized and unused variables
scripts:
. new packaging system
pm: fixed rebooting by making a copy of the monitor code from the user
process. this is necessary because that process is dead by the time
sys_abort() is called.
also added more info to the "can't reply" panic.
'who', indicating caller number in pm and fs and some other servers, has
been removed in favour of 'who_e' (endpoint) and 'who_p' (proc nr.).
In both PM and FS, isokendpt() convert endpoints to process slot
numbers, returning OK if it was a valid and consistent endpoint number.
okendpt() does the same but panic()s if it doesn't succeed. (In PM,
this is pm_isok..)
pm and fs keep their own records of process endpoints in their proc tables,
which are needed to make kernel calls about those processes.
message field names have changed.
fs drivers are endpoints.
fs now doesn't try to get out of driver deadlock, as the protocol isn't
supposed to let that happen any more. (A warning is printed if ELOCKED
is detected though.)
fproc[].fp_task (indicating which driver the process is suspended on)
became an int.
PM and FS now get endpoint numbers of initial boot processes from the
kernel. These happen to be the same as the old proc numbers, to let
user processes reach them with the old numbers, but FS and PM don't know
that. All new processes after INIT, even after the generation number
wraps around, get endpoint numbers with generation 1 and higher, so
the first instances of the boot processes are the only processes ever
to have endpoint numbers in the old proc number range.
More return code checks of sys_* functions have been added.
IS has become endpoint-aware. Ditched the 'text' and 'data' fields
in the kernel dump (which show locations, not sizes, so aren't terribly
useful) in favour of the endpoint number. Proc number is still visible.
Some other dumps (e.g. dmap, rs) show endpoint numbers now too which got
the formatting changed.
PM reading segments using rw_seg() has changed - it uses other fields
in the message now instead of encoding the segment and process number and
fd in the fd field. For that it uses _read_pm() and _write_pm() which to
_taskcall()s directly in pm/misc.c.
PM now sys_exit()s itself on panic(), instead of sys_abort().
RS also talks in endpoints instead of process numbers.
Implemented by changing write_map to accept a WMAP_FREE flag. In that
case, it doesn't update the datablock (creating indirect zones as
necessary) pointer, but it frees the datablock if present. Also it
frees the single and double indirect blocks if unused.
This makes the implementation of truncate_inode() simpler.
truncate_inode() now accepts a truncation length which makes
implementing truncate() and ftruncate() simple.
This also allowed implementing the F_FREESP fcntl().
. new_node() now returns inode of parent dir as argument that
has to be put_node()d again by the caller of new_node().
it can also return the name of the last component as last_dir()
did.
. advance() takes a pointer to a pointer of an inode as the
parent now. This parent can change, in which case the old
one is put_node()d and a new one is put there.
. eat_path() replaced by more flexible parse_path()
. last_dir() replaced by call to parse_path().
. do_slink(), do_readlink(), do_lstat() and slink_traverse() added.
Also added some truncate()/ftruncate()-introduction related changes.
(e.g. renamed truncate() to truncate_inode().)
