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

From: Nam Cao <namcao@linutronix.de>
To: Palmer Dabbelt <palmer@dabbelt.com>
Cc: bigeasy@linutronix.de, tglx@linutronix.de,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org,
	x86@kernel.org, hpa@zytor.com, aou@eecs.berkeley.edu,
	bp@alien8.de, Catalin Marinas <catalin.marinas@arm.com>,
	williams@redhat.com, dave.hansen@linux.intel.com,
	mingo@redhat.com, john.ogness@linutronix.de,
	Paul Walmsley <paul.walmsley@sifive.com>,
	pmladek@suse.com, senozhatsky@chromium.org, rostedt@goodmis.org,
	Will Deacon <will@kernel.org>
Subject: Re: [PATCH 3/3] riscv: Allow to enable PREEMPT_RT.
Date: Wed, 9 Oct 2024 19:41:53 +0200	[thread overview]
Message-ID: <20241009174153.Hk5MGakp@linutronix.de> (raw)
In-Reply-To: <mhng-f0f516a0-6774-4c87-b8da-313601bad133@palmer-ri-x1c9>

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@linutronix.de 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@linutronix.de>
> > > 
> > > With the printk patches applied:
> > > 
> > > Tested-by: Nam Cao <namcao@linutronix.de> # 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@rivosinc.com>
> > 
> > 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@linutronix.de/

Any chance this fixes your issue as well?

Best regards,
Nam

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