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

From	Mikulas Patocka <mpatocka@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [tip:x86/urgent] x86/PAT: Fix Xorg regression on CPUs that don't support PAT
Date	2017-05-30 20:00 +0200
Message-ID	<tMTB0-1Xw-19@gated-at.bofh.it> (permalink)
References	(1 earlier) <tKBId-15d-3@gated-at.bofh.it> <tMbgC-5BS-17@gated-at.bofh.it> <tMbqh-5Fh-3@gated-at.bofh.it> <tMBNL-6Il-5@gated-at.bofh.it> <tMT7X-1Nk-1@gated-at.bofh.it>
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On Tue, 30 May 2017, Dominik Brodowski wrote:

> 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.

It is interesting - does it mean that the boot cpu does have PAT and the 
secondary CPUs don't? Please send /proc/cpuinfo with all the cores active.

This part of the patch is not required anyway, so I will resubmit the 
patch with this part disabled (and with an added call to 
init_cache_modes() as Andy suggested).

Mikulas

> > 3. use the full PAT patch and apply the below patch on the top of it.
> 
> No joy.
> 
> 
> Best,
> 	Dominik
>

Thread

Re: [tip:x86/urgent] x86/PAT: Fix Xorg regression on CPUs that don't  support PAT Bernhard Held <berny156@gmx.de> - 2017-05-28 20:40 +0200
  Re: [tip:x86/urgent] x86/PAT: Fix Xorg regression on CPUs that don't  support PAT Andy Lutomirski <luto@kernel.org> - 2017-05-28 20:50 +0200
    Re: [tip:x86/urgent] x86/PAT: Fix Xorg regression on CPUs that don't  support PAT Mikulas Patocka <mpatocka@redhat.com> - 2017-05-30 01:00 +0200
      Re: [tip:x86/urgent] x86/PAT: Fix Xorg regression on CPUs that don't  support PAT Dominik Brodowski <linux@dominikbrodowski.net> - 2017-05-30 19:30 +0200
        Re: [tip:x86/urgent] x86/PAT: Fix Xorg regression on CPUs that don't  support PAT Mikulas Patocka <mpatocka@redhat.com> - 2017-05-30 20:00 +0200
          Re: [tip:x86/urgent] x86/PAT: Fix Xorg regression on CPUs that don't  support PAT Dominik Brodowski <linux@dominikbrodowski.net> - 2017-05-30 20:50 +0200
          Re: [tip:x86/urgent] x86/PAT: Fix Xorg regression on CPUs that don't  support PAT Bernhard Held <berny156@gmx.de> - 2017-05-30 21:40 +0200
          Re: [tip:x86/urgent] x86/PAT: Fix Xorg regression on CPUs that  don't support PAT Junichi Nomura <j-nomura@ce.jp.nec.com> - 2017-05-31 11:50 +0200
    [PATCH v2] X86: don't report PAT on CPUs that don't support it Mikulas Patocka <mpatocka@redhat.com> - 2017-06-07 00:50 +0200
      Re: [PATCH v2] X86: don't report PAT on CPUs that don't support it Andy Lutomirski <luto@kernel.org> - 2017-06-07 01:00 +0200
        Re: [PATCH v2] X86: don't report PAT on CPUs that don't support it Mikulas Patocka <mpatocka@redhat.com> - 2017-06-07 01:30 +0200

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