/* $NetBSD: TODO,v 1.25 2018/02/03 21:45:54 palle Exp $ */

Things to be done:

common:
- make %g6 point to curcpu
- make %g7 point to curlwp
- change run-time checks for cpu type to function pointers

sun4u:
- GENERIC.UP kernel hangs on v445 (missing interrupt?)

sun4v:
 - current status: The kernel boots and starts the init process (syscalls are done, but crashes...) (*)
- 64-bit kernel support
- 32-bit kernel support
- libkvm
- ofwboot: tlb_init_sun4v() hardcodes number of slots to 64
- locore.s: sun4v_datatrap missing implementation for trap level 1
- check build without SUN4V defined
- replace relevant references to %ver with GET_MAXCWP
- pmap_mp_init(): sun4v missing handling
- replace constructs like "wrpr %g0, PSTATE_KERN, %pstate" with NORMAL_GLOBALS
- replace constructs line "wrpr %g0, PSTATE_INTR, %pstate" with ALTERNATE_GOBALS
- sun4v tsb no need to lock... per cpu... anyway...
- ci_tsb_desc->td_ctxidx: -1 or 1?
- MP support - currently bypassed in pmap_bootstrap() for sun4v
- vpci.c/vpcivar.h: cleanup FIXMEs
- interrups not handled properly (com at ebus only...)
- mpt(4) complains: mpt0: Phy 0: Link Status Unknown
- man pages for drivers imported from OpenBSD lke vpci, vbus, cbus, vdsk, ldc etc.
- vdsk and ldc drivers: code maked with OPENBSD_BUSDMA - make the bus_dma stuff work properly
- vbus.c: handle prom_getprop() memory leaks
- locore.s: rft_user (sun4v specific manaul fill) - seems to work, but is it good enough (compared to openbsds rft_user?


(*)
The current state of the code crashes in the code path after the init process
(pid 1) does a fork(), starting pid 2.
A new lwp is created and lwp_trampoline() is called which in turn calls 
return_from_trap(). Here the code path continues to rft_user().
A trap (0x68 - this is a Hyper-Priv trap...) occurs in rft_user_fault_start()
where the FILL() macro causes the trap trying to load the local register %l0 
from the stack using ASI AIUS (%o6 contains 0xffffffffffffcd91).
The Hyper-Priv trap 0x68 is transformed to a Priv trap 0x31, causing 
sun4v_dtsb_miss() to be called, continuing to sun4v_datatrap().
Here TRAP_SETUP() is called, 
The windows registers are now:  %otherwin=0, %cansave=6, canrestore=0.
Part of the TRAP_SETUP() code will do a 'save %g6, 0, %sp', 
The windows registers are now:  %otherwin=0, %cansave=5, canrestore=1.
TRAP_SETUP() now updates %otherwin with the values of %canrestore and clears 
%canrestore, so the windows registers are now: %otherwin=1, %cansave=5, 
canrestore=0.
The execution continues to data_access_fault() and further down the call stack
with function calls until %cansave reaches 0 causing a spill trap 
(0xa8 - spill_2_other). The contents of the %sp register is 0x00000000e00xxxxx.
%wstate is (octal) 26.
The windows registers are now:  %otherwin=1, %cansave=0, canrestore=5.
The spill code is using ASI AIUS. spill_2_other is selected since %otherwin is
non-zero, so the index in wstate.other is 2 (spill_2_other).
SPILLBOTH() is invoked, using ASI AIUS. While storing %l0 to %sp+0x7ff 
(%sp is 0xffffffffffffcd91) a new trap occurs, 0x68 (Hyper-priv, e.g. 0x31 Priv)
at trap level 2 causing the trap level to go to 3. This is above the mx trap
level for sun4v which is 2...
So... the first access to 0xffffffffffffcd91 causes a cyclic access to
0xffffffffffffcd91 again causing the max trap level to exceed.
hm....how to fix this..........