* Userspace change to use the new kernel calls
- _taskcall(SYSTASK...) changed to _kernel_call(...)
- int 32 reused for the kernel calls
- _do_kernel_call() to make the trap to kernel
- kernel_call() to make the actuall kernel call from C using
_do_kernel_call()
- unlike ipc call the kernel call always succeeds as kernel is
always available, however, kernel may return an error
* Kernel side implementation of kernel calls
- the SYSTEm task does not run, only the proc table entry is
preserved
- every data_copy(SYSTEM is no data_copy(KERNEL
- "locking" is an empty operation now as everything runs in
kernel
- sys_task() is replaced by kernel_call() which copies the
message into kernel, dispatches the call to its handler and
finishes by either copying the results back to userspace (if
need be) or by suspending the process because of VM
- suspended processes are later made runnable once the memory
issue is resolved, picked up by the scheduler and only at
this time the call is resumed (in fact restarted) which does
not need to copy the message from userspace as the message
is already saved in the process structure.
- no ned for the vmrestart queue, the scheduler will restart
the system calls
- no special case in do_vmctl(), all requests remove the
RTS_VMREQUEST flag
. added safecopies.c:
these are library functions to maintain grant tables in own address space
. sys_safecopy.c:
interfaces to kernel calls to perform safe copy functions in from or to
foreign process
. changes in i/o fields (type merged with request) reflected in
library functions (sys_out.c, sys_vinb.c, sys_vinl.c, sys_vinw.c,
sys_voutb.c, sys_voutl.c, sys_voutw.c)
. type merged with request in sys_sdevio, also now accepts offset which
is used when a grant is specified (the _DIO_SAFE subtype)
. system printf() function changed to send DIAGNOSTICS_S messages, which
specify a grant id instead of a direct address for the buffer to be
printed; tty and log can then safecopy the buffer
