Re: [PATCH 3/3] riscv: Allow to enable PREEMPT_RT.

[Nam Cao]

On Wed, Oct 09, 2024 at 09:44:59AM -0700, Palmer Dabbelt wrote:
> On Fri, 06 Sep 2024 11:48:03 PDT (-0700), Palmer Dabbelt wrote:
> > On Fri, 06 Sep 2024 08:13:24 PDT (-0700), namcao@xxxxxxxxxxxxx wrote:
> > > On Fri, Sep 06, 2024 at 12:59:06PM +0200, Sebastian Andrzej Siewior wrote:
> > > > It is really time.
> > > > 
> > > > riscv has all the required architecture related changes, that have been
> > > > identified over time, in order to enable PREEMPT_RT. With the recent
> > > > printk changes, the last known road block has been addressed.
> > > > 
> > > > Allow to enable PREEMPT_RT on riscv.
> > > > 
> > > > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> > > 
> > > With the printk patches applied:
> > > 
> > > Tested-by: Nam Cao <namcao@xxxxxxxxxxxxx> # Visionfive 2
> > 
> > 
> > Thanks.  LMK if you guys want me to take this through the RISC-V tree,
> > but no big deal if you want it somewhere else -- and if there's some
> > dependencies already going in through some sort of RT tree maybe that's
> > just easier.  So
> > 
> > Acked-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
> > 
> > I don't have a test setup yet, but I figure it's a new feature so I'll
> > just flip it on as a config post-rc1.  Presumably this just works in the
> > QEMU virt board, or is there some wizardry I'll need to copy?
> 
> and it breaks my boot test script.  Looks like it's actually working mostly
> fine, I'm just not getting the "reboot: System halted" message that I'm
> checking for to make sure the system actually went down cleanly.
> 
> I'm not sure if this is expected behavior in RT land, or if we've got some
> sort of bug.  It sort of smells like we're losing the last printk() line...

I also had some occasional problem with rebooting my Visionfive 2 board,
which was fixed with:
https://lore.kernel.org/lkml/20241003084152.2422969-1-namcao@xxxxxxxxxxxxx/

Any chance this fixes your issue as well?

Best regards,
Nam