This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


[Xen-devel] Re: [PATCH, experimental] i386 Allow the fixmap to be reloca

To: Zachary Amsden <zach@xxxxxxxxxx>
Subject: [Xen-devel] Re: [PATCH, experimental] i386 Allow the fixmap to be relocated at boot time
From: Chris Wright <chrisw@xxxxxxxx>
Date: Fri, 5 Aug 2005 17:22:06 -0700
Cc: Chris Wright <chrisw@xxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, virtualization@xxxxxxxxxxxxxx
Delivery-date: Sat, 06 Aug 2005 00:20:28 +0000
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <42F3FFBA.3040009@xxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <42F3F61F.30305@xxxxxxxxxx> <20050805234655.GY7762@xxxxxxxxxxxxxxxxxxx> <42F3FFBA.3040009@xxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mutt/1.5.6i
* Zachary Amsden (zach@xxxxxxxxxx) wrote:
> Your patch looks good, although the minimal change to subarch is to 
> merely have __FIXADDR_TOP defined by the sub-architecture.  Is there any 
> additional benefit to moving the fixmaps into the subarch - i.e. moving 
> subarch-specific pieces out of mach-default?

As you've identified, so subarch can put whatever wonky junk
it needs in there.

> I guess there is.  For example include/asm-i386/mach-visws/mach_fixmap.h 
> could do this:
>        FIX_CO_CPU,     /* Cobalt timer */ \
>        FIX_CO_APIC,    /* Cobalt APIC Redirection Table */ \
>        FIX_LI_PCIA,    /* Lithium PCI Bridge A */ \
>        FIX_LI_PCIB,    /* Lithium PCI Bridge B */
> Then include/asm-i386/fixmap.h includes <mach_fixmap.h>, for which the 
> default is an empty define for SUBARCH_FIXMAPS.


> Also, it seems reasonable that people may want to poke holes in high 
> linear space for other hypervisor projects, research, or performance 
> reasons without having to build a custom sub-architecture just for 
> that.  So I think there is some benefit to making the hole size a 
> general configurable option (with defaults depending on the sub-arch you 
> select).

It needs to have tangible value for in-tree code.  Seems worthwhile to
play with it a bit though.


Xen-devel mailing list