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From: "Lendacky, Thomas" <Thomas.Lendacky@amd.com>
To: Thomas Gleixner <tglx@linutronix.de>,
	"Li, Aubrey" <aubrey.li@linux.intel.com>
Cc: Aubrey Li <aubrey.intel@gmail.com>,
	Daniel Drake <drake@endlessm.com>,
	"x86@kernel.org" <x86@kernel.org>, 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 15:44:19 +0000	[thread overview]
Message-ID: <3d14b0cc-3cca-1874-3521-4ee2ec52141d@amd.com> (raw)
In-Reply-To: <alpine.DEB.2.21.1908011054210.1965@nanos.tec.linutronix.de>

On 8/1/19 5:13 AM, Thomas Gleixner wrote:
> On Thu, 1 Aug 2019, Li, Aubrey wrote:
>> On 2019/8/1 16:13, Thomas Gleixner wrote:
>>> 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.
>>>
>> Yeah, I should specify, Daniel, your platform needs a global clock event, ;-)
> 
> Care to look at the manuals before making assumptions?
> 
>   2.1.9 Timers
> 
>    Each core includes the following timers. These timers do not vary in
>    frequency regardless of the current P-state or C-state.
> 
>    * Core::X86::Msr::TSC; the TSC increments at the rate specified by the
>      P0 Pstate. See Core::X86::Msr::PStateDef.
> 
>    * The APIC timer (Core::X86::Apic::TimerInitialCount and
>      Core::X86::Apic::TimerCurrentCount), which increments at the rate of
>      2xCLKIN; the APIC timer may increment in units of between 1 and 8.
> 
> The Ryzens use a 100MHz input clock for the APIC normally, but I'm not sure
> whether this is subject to overclocking. If so then it should be possible
> to figure that out somehow. Tom?

Let me check with the hardware folks and I'll get back to you.

Thanks,
Tom

> 
> Thanks,
> 
> 	tglx
> 

  reply	other threads:[~2019-08-01 15:45 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 [this message]
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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