From: Thomas Gleixner <tglx@linutronix.de>
To: Aubrey Li <aubrey.intel@gmail.com>
Cc: Daniel Drake <drake@endlessm.com>,
x86@kernel.org, "Li, Aubrey" <aubrey.li@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Endless Linux Upstreaming Team <linux@endlessm.com>
Subject: Re: setup_boot_APIC_clock() NULL dereference during early boot on reduced hardware platforms
Date: Thu, 1 Aug 2019 10:13:31 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.21.1908011011250.1788@nanos.tec.linutronix.de> (raw)
In-Reply-To: <CAERHkrtaVAQHDU1cj2_GLL59LPjp7E=3X0Zna0spfFB=Ve5__w@mail.gmail.com>
On Thu, 1 Aug 2019, Aubrey Li wrote:
> On Thu, Aug 1, 2019 at 3:35 PM Thomas Gleixner <tglx@linutronix.de> wrote:
> >
> > On Thu, 1 Aug 2019, Aubrey Li wrote:
> > > On Thu, Aug 1, 2019 at 2:26 PM Daniel Drake <drake@endlessm.com> wrote:
> > > > global_clock_event is NULL here. This is a "reduced hardware" ACPI
> > > > platform so acpi_generic_reduced_hw_init() has set timer_init to NULL,
> > > > avoiding the usual codepaths that would set up global_clock_event.
> > > >
> > > IIRC, acpi_generic_reduced_hw_init() avoids initializing PIT, the status of
> > > this legacy device is unknown in ACPI hw-reduced mode.
> > >
> > > > I tried the obvious:
> > > > if (!global_clock_event)
> > > > return -1;
> > > >
> > > No, the platform needs a global clock event, can you turn on some other
> >
> > Wrong. The kernel boots perfectly fine without a global clock event. But
> > for that the TSC and LAPIC frequency must be known.
>
> I think LAPIC fast calibrate is only supported on intel platform, while
> Daniel's box is an AMD platform. That's why lapic_init_clockevent() failed
> and fall into the code path which needs a global clock event.
We know that.
The point is that it does not matter which vendor a CPU comes from. The
kernel does support legacyless boot when the frequencies are known. Whether
that's currently possible on that particular CPU is a different question.
Thanks,
tglx
next prev parent reply other threads:[~2019-08-01 8:13 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-01 6:24 setup_boot_APIC_clock() NULL dereference during early boot on reduced hardware platforms Daniel Drake
2019-08-01 7:16 ` Aubrey Li
2019-08-01 7:35 ` Thomas Gleixner
2019-08-01 7:56 ` Aubrey Li
2019-08-01 8:13 ` Thomas Gleixner [this message]
2019-08-01 8:21 ` Li, Aubrey
2019-08-01 10:13 ` Thomas Gleixner
2019-08-01 15:44 ` Lendacky, Thomas
2019-08-08 20:36 ` Thomas Gleixner
2019-08-08 21:01 ` Lendacky, Thomas
2019-08-08 21:08 ` Thomas Gleixner
2019-08-08 21:36 ` Lendacky, Thomas
2019-08-09 12:54 ` [PATCH] x86/apic: Handle missing global clockevent gracefully Thomas Gleixner
2019-08-09 12:59 ` Jiri Slaby
2019-08-09 13:58 ` Lendacky, Thomas
2019-08-09 19:40 ` Thomas Gleixner
2019-08-12 6:16 ` Daniel Drake
2019-08-12 7:03 ` Jiri Slaby
2019-08-15 5:02 ` Daniel Drake
2019-08-12 7:46 ` Li, Aubrey
2019-08-12 12:24 ` Thomas Gleixner
2019-08-12 12:59 ` Aubrey Li
2019-08-12 17:11 ` Thomas Gleixner
2019-08-19 10:37 ` [tip:x86/urgent] " tip-bot for Thomas Gleixner
2019-08-01 9:00 ` setup_boot_APIC_clock() NULL dereference during early boot on reduced hardware platforms Daniel Drake
2019-08-01 10:17 ` Thomas Gleixner
2019-08-01 7:27 ` Thomas Gleixner
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