Re: [tip:x86/urgent] x86/PAT: Fix Xorg regression on CPUs that don't support PAT

From: Dominik Brodowski <linux@dominikbrodowski.net>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: Bernhard Held <berny156@gmx.de>,
	Andy Lutomirski <luto@kernel.org>, Toshi Kani <toshi.kani@hp.com>,
	Borislav Petkov <bp@alien8.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Brian Gerst <brgerst@gmail.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	"Luis R. Rodriguez" <mcgrof@suse.com>,
	Denys Vlasenko <dvlasenk@redhat.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [tip:x86/urgent] x86/PAT: Fix Xorg regression on CPUs that don't support PAT
Date: Tue, 30 May 2017 19:14:40 +0200	[thread overview]
Message-ID: <20170530171440.GA1599@light.dominikbrodowski.net> (raw)
In-Reply-To: <alpine.LRH.2.02.1705291837130.1640@file01.intranet.prod.int.rdu2.redhat.com>

[-- Attachment #1: Type: text/plain, Size: 750 bytes --]

Same boot problem here (Intel(R) Core(TM) i5-5200U CPU on a Dell XPS 13),
git-bisected to the same patch...

On Mon, May 29, 2017 at 06:50:57PM -0400, Mikulas Patocka wrote:
> Please do the following three tests and test if the kernel boots.
> 
> 1. use the PAT patch and revert the change to the function pat_enabled()
> - i.e. change it to the original:
> bool pat_enabled(void)
> {
> 	return !!__pat_enabled;
> }

No joy.

> 2. use the PAT patch and revert the change to the function pat_ap_init
> - i.e. change it to the original:
> static void pat_ap_init(u64 pat)
> {
> 	if (!boot_cpu_has(X86_FEATURE_PAT)) {

Joy.

> 3. use the full PAT patch and apply the below patch on the top of it.

No joy.

Best,
	Dominik

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]