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From: Daniel Drake <drake@endlessm.com>
To: Aubrey Li <aubrey.intel@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	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 17:00:23 +0800	[thread overview]
Message-ID: <CAD8Lp452GdoL-Bt7rSP=u3RKEZ2H3qm3LvKfe=cCsjP0biG_sQ@mail.gmail.com> (raw)
In-Reply-To: <CAERHkruxfBc8DqNUr=fbYuQWrXrHC7cK6HnVR3xp0iLA9QtxiQ@mail.gmail.com>

On Thu, Aug 1, 2019 at 3:16 PM Aubrey Li <aubrey.intel@gmail.com> wrote:
> No, the platform needs a global clock event, can you turn on some other
> clock source on your platform, like HPET?

Thanks Audrey and Thomas for the quick hints!

I double checked under Windows - it seems to be using a HPET there.
Also there is the HPET ACPI table. So I think this is the right angle
to look at.

Under Linux, hpet_legacy_clockevent_register() is the function where
global_clock_event can be set to HPET.

However, the only way this can be called is from hpet_enable().

hpet_enable() is called from 2 places:
 1. From hpet_time_init(). This is the default x86 timer_init that
acpi_generic_reduced_hw_init() took out of action here.
 2. From hpet_late_init(). However that function is only called late,
after calibrate_APIC_clock() has already crashed the kernel. Also,
even if moved earlier it would also not call hpet_enable() here
because the ACPI HPET table parsing has already populated
hpet_address.

I tried slotting in a call to hpet_enable() at an earlier point
regardless, but I still end up with the kernel hanging later during
boot, probably because irq0 fails to be setup and this error is hit:
    if (setup_irq(0, &irq0))
        pr_info("Failed to register legacy timer interrupt\n");

I'll go deeper into that; further hints welcome too.

Thanks
Daniel

  parent reply	other threads:[~2019-08-01  9:00 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-01  6:24 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
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   ` Daniel Drake [this message]
2019-08-01 10:17     ` setup_boot_APIC_clock() NULL dereference during early boot on reduced hardware platforms Thomas Gleixner
2019-08-01  7:27 ` Thomas Gleixner

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