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From: Chris Wright <chrisw@osdl.org>
To: Zachary Amsden <zach@vmware.com>
Cc: Andrew Morton <akpm@osdl.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Virtualization Mailing List <virtualization@lists.osdl.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Zwane Mwaikambo <zwane@arm.linux.org.uk>,
	Chris Wright <chrisw@osdl.org>, Martin Bligh <mbligh@mbligh.org>,
	Pratap Subrahmanyam <pratap@vmware.com>,
	Christopher Li <chrisl@vmware.com>
Subject: Re: [PATCH 5/5] Create a hole in high linear address space
Date: Wed, 24 Aug 2005 13:19:20 -0700	[thread overview]
Message-ID: <20050824201920.GN7762@shell0.pdx.osdl.net> (raw)
In-Reply-To: <200508241845.j7OIjIeM001900@zach-dev.vmware.com>

* Zachary Amsden (zach@vmware.com) wrote:
> Allow compile time creation of a hole at the high end of linear address space.
> This makes accomodating a hypervisor a much more tractable problem by giving
> it ample playground to live in.  Currently, the hole size is fixed at config
> time; I have experimented with dynamically sized holes, and have a later
> patch that developes this potential, but it becomes much more useful once
> the exact negotiation of linear address space with the hypervisor is defined.
> 
> The fixed compile time solution is sufficient for now.

Xen moves __FIXADDR_TOP like this:

#ifdef CONFIG_X86_PAE
# define HYPERVISOR_VIRT_START (0xF5800000UL)
#else
# define HYPERVISOR_VIRT_START (0xFC000000UL)
#endif

and

#define __FIXADDR_TOP  (HYPERVISOR_VIRT_START - 2 * PAGE_SIZE)

and also adds bits to fixmap.

So this proposed mechanism isn't quite good enough.

thanks,
-chris

  reply	other threads:[~2005-08-24 20:19 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-08-24 18:45 [PATCH 5/5] Create a hole in high linear address space Zachary Amsden
2005-08-24 20:19 ` Chris Wright [this message]
2005-08-24 21:18   ` Zachary Amsden
2005-08-24 21:28     ` Chris Wright

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