Re: NetBSD on Sun T5220

[Palle Lyckegaard <palle%freeshell.org@localhost>]

On Sun, 5 Oct 2025, Sad Clouds wrote:

> > I have identified a potential issue in the locore.s file (pcbspill) where
> > %otherwin > 1 is not handles properly (at least in the sun4v issue I have
> > been debugging).
> >
> > I should be able to provide a patch within a day or two - still unsure if
> > it fixes the issue 100% though and does not cause regression for sun4u.

Hello.

Here is my first attempt to fix the issue.

I'm still not 100% sure that it works as expected, but please give it a 
try and report back your results.

The code in 'pcbspill' is sun4v-only, so no impact on sun4u.

Regards
Palle


diff --git a/sys/arch/sparc64/sparc64/locore.s 
b/sys/arch/sparc64/sparc64/locore.s
index 72718a8197db..d12b15fa972f 100644
--- a/sys/arch/sparc64/sparc64/locore.s
+++ b/sys/arch/sparc64/sparc64/locore.s
@@ -3469,13 +3469,25 @@ pcbspill:
        lduba   [%g6 + PCB_NSAVED] %asi, %g7            ! Fetch current 
nsaved from the pcb
        sllx    %g7, 7, %g5                             ! 8+8 registers 
each 8 bytes = 128 bytes (2^7)
        add     %g6, %g5, %g5                           ! Offset into 
pcb_rw
+1:
        SPILL   stxa, %g5 + PCB_RW, 8, %asi             ! Store the locals 
and ins
-       saved

-       sllx    %g7, 3, %g5
-       add     %g6, %g5, %g5
+       add     %g5, 16*8, %g5                          ! Next location 
for saved register windows

-       inc     %g7
+       stxa    %o6, [%g5 + PCB_RW + (14*8)] %asi       ! Save %sp so we 
can write these all out
+
+       saved                                           ! Increments 
%cansave and decrements %otherwin
+
+       rdpr    %cwp, %g1                               ! shift register 
window forward
+       inc     %g1
+       wrpr    %g1, %cwp
+
+       inc     %g7                                     ! increment number 
of saved register windows
+
+       rdpr    %otherwin, %g1                          ! Check to see if 
done spill'ing otherwin
+       brnz,pt %g1, 1b
+        nop
+
        stba    %g7, [%g6 + PCB_NSAVED] %asi

        retry