On 12/28/2014 08:20 AM, Пламен Петров wrote:
-----Original Message-----
From: Juergen Gross [mailto:jgr...@suse.com]
Sent: Saturday, December 27, 2014 3:48 PM
To: Пламен Петров; linux-kernel@vger.kernel.org
Cc: 'Thomas Gleixner'
Subject: Re: [BISECTED] 3.19-rc1 regression - kernel does not load in GRUB
0.97 (GRUB Legacy)
On 12/24/2014 01:28 AM, Пламен Петров wrote:
Hello!
I use GRUB Legacy bootloader (version 0.97) on a couple machines, and
where 3.18.x loads fine, 3.19-rc1 does not.
While compiling I used the attached .config file accompanied by "make
olddefconfig"
Can you tell me something about the hardware (processor model)?
You are not booting the system under VMWare by any chance?
As a matter of fact - I am compiling in a VMware Player (6.0.3
build-1895310) virtual machine, boot testing there, and then if everything
is OK, I transfer the monolithic kernel produced on 3 virtual machines that
run on EXSi and 2 actual servers. So along those lines - the failing
3.19-rc1 never saw actual hardware - it was all tested (and bisected) inside
a VM.
Thanks. VMWare having problems with my patch is a known issue. I've
already sent a patch working around that issue (VMWare has a bug
emulating the PAT MSR). You can either use that patch (attached for
your convenience) or use the "nopat" option.
Juergen
>From 4b65fb80338c71673cabfa9fa9b0f80f5a4bc320 Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgr...@suse.com>
Date: Tue, 16 Dec 2014 07:43:51 +0100
Subject: [PATCH] x86: don't rely on VMWare emulating PAT MSR correctly
VMWare seems not to emulate the PAT MSR correctly: reaeding
MSR_IA32_CR_PAT returns 0 even after writing another value to it.
Detect this bug and don't use the read value if it is 0.
Commit bd809af16e3ab1f8d55b3e2928c47c67e2a865d2 ("x86: Enable PAT to
use cache mode translation tables") triggers this VMWare bug when the
kernel is booted as a VMWare guest.
Reported-by: Jongman Heo <jongman....@samsung.com>
Signed-off-by: Juergen Gross <jgr...@suse.com>
Tested-by: Jongman Heo <jongman....@samsung.com>
---
arch/x86/mm/pat.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index edf299c..7ac6869 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -234,8 +234,13 @@ void pat_init(void)
PAT(4, WB) | PAT(5, WC) | PAT(6, UC_MINUS) | PAT(7, UC);
/* Boot CPU check */
- if (!boot_pat_state)
+ if (!boot_pat_state) {
rdmsrl(MSR_IA32_CR_PAT, boot_pat_state);
+ if (!boot_pat_state) {
+ pat_disable("PAT read returns always zero, disabled.");
+ return;
+ }
+ }
wrmsrl(MSR_IA32_CR_PAT, pat);
--
2.1.2
