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From: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
To: Zachary Amsden <zach-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>
Cc: kvm-devel
	<kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Andi Kleen <ak-l3A5Bk7waGM@public.gmane.org>,
	Virtualization Mailing List
	<virtualization-qjLDD68F18O7TbgM5vRIOg@public.gmane.org>,
	Jim Mattson <jmattson-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>,
	Gabriel Barazer <gabriel-KSe8qvLY914@public.gmane.org>
Subject: Re: 2.6.22 x86_64 : kernel initial decompression hangs on vmware
Date: Thu, 09 Aug 2007 23:57:48 +0300	[thread overview]
Message-ID: <46BB7FCC.4040509@qumranet.com> (raw)
In-Reply-To: <46B4A7E4.4030907-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>

Zachary Amsden wrote:
>
> Since I was just involved in the boot decompressor for another bug, I 
> took a look at this.  2.6.22 switches it to be 64-bit code.  VT is 
> very picky about what state it can run in.  Not using VT on Intel 
> 64-bit hardware cripples performance, running at far below normal 
> speed, and taking minutes to decompress the kernel, which is nearly 
> instantaneous otherwise.
>
> To get back into VT in this case, not only do we need to load FS and 
> GS, we also need to setup an initial LDT and task.  Can you try the 
> attached patch and see that it does the right thing?
>
> I've also cc'd the KVM developers, as the same problem will affect 
> them, and hopefully the same patch will fix it.
>

We haven't seen any issue with the 2.6.22 boot decompressor.  Which of 
the four (fs, gs, ldt, or tr) were proving problematic and why?



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WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi@qumranet.com>
To: Zachary Amsden <zach@vmware.com>
Cc: Gabriel Barazer <gabriel@oxeva.fr>, Andi Kleen <ak@suse.de>,
	Jim Mattson <jmattson@vmware.com>,
	linux-kernel@vger.kernel.org,
	Virtualization Mailing List <virtualization@lists.osdl.org>,
	kvm-devel <kvm-devel@lists.sourceforge.net>
Subject: Re: 2.6.22 x86_64 : kernel initial decompression hangs on vmware
Date: Thu, 09 Aug 2007 23:57:48 +0300	[thread overview]
Message-ID: <46BB7FCC.4040509@qumranet.com> (raw)
In-Reply-To: <46B4A7E4.4030907@vmware.com>

Zachary Amsden wrote:
>
> Since I was just involved in the boot decompressor for another bug, I 
> took a look at this.  2.6.22 switches it to be 64-bit code.  VT is 
> very picky about what state it can run in.  Not using VT on Intel 
> 64-bit hardware cripples performance, running at far below normal 
> speed, and taking minutes to decompress the kernel, which is nearly 
> instantaneous otherwise.
>
> To get back into VT in this case, not only do we need to load FS and 
> GS, we also need to setup an initial LDT and task.  Can you try the 
> attached patch and see that it does the right thing?
>
> I've also cc'd the KVM developers, as the same problem will affect 
> them, and hopefully the same patch will fix it.
>

We haven't seen any issue with the 2.6.22 boot decompressor.  Which of 
the four (fs, gs, ldt, or tr) were proving problematic and why?



  parent reply	other threads:[~2007-08-09 20:57 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-07-26  0:08 2.6.22 x86_64 : kernel initial decompression hangs on vmware Gabriel Barazer
2007-07-26  0:19 ` Zachary Amsden
     [not found] ` <46A7E606.4030001-KSe8qvLY914@public.gmane.org>
2007-08-04 16:23   ` Zachary Amsden
2007-08-04 16:23     ` Zachary Amsden
     [not found]     ` <46B4A7E4.4030907-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>
2007-08-04 17:18       ` Gabriel Barazer
2007-08-04 17:18         ` Gabriel Barazer
2007-08-09 20:57       ` Avi Kivity [this message]
2007-08-09 20:57         ` Avi Kivity
     [not found]         ` <46BB7FCC.4040509-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-08-09 23:28           ` Zachary Amsden
2007-08-09 23:28             ` Zachary Amsden
2007-08-10  1:48             ` Avi Kivity

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