[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Xen-devel] Re: [RFC, PATCH 16/24] i386 Vmi io header
- To: Zachary Amsden <zach@xxxxxxxxxx>
- From: ebiederm@xxxxxxxxxxxx (Eric W. Biederman)
- Date: Wed, 15 Mar 2006 14:17:32 -0700
- Cc: Andrew Morton <akpm@xxxxxxxx>, Joshua LeVasseur <jtl@xxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Pratap Subrahmanyam <pratap@xxxxxxxxxx>, Wim Coekaerts <wim.coekaerts@xxxxxxxxxx>, Chris Wright <chrisw@xxxxxxxx>, Jack Lo <jlo@xxxxxxxxxx>, Zachary Amsden <zach@xxxxxxxxxx>, Dan Hecht <dhecht@xxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxxxx>, Christopher Li <chrisl@xxxxxxxxxx>, Virtualization Mailing List <virtualization@xxxxxxxxxxxxxx>, Linus Torvalds <torvalds@xxxxxxxx>, Anne Holler <anne@xxxxxxxxxx>, Jyothy Reddy <jreddy@xxxxxxxxxx>, Kip Macy <kmacy@xxxxxxxxxxx>, Ky Srinivasan <ksrinivasan@xxxxxxxxxx>, Leendert van Doorn <leendert@xxxxxxxxxxxxxx>, Dan Arai <arai@xxxxxxxxxx>
- Delivery-date: Fri, 17 Mar 2006 10:37:13 +0000
- List-id: Xen developer discussion <xen-devel.lists.xensource.com>
Zachary Amsden <zach@xxxxxxxxxx> writes:
> Move I/O instruction building to the sub-arch layer. Some very crafty
> but esoteric macros are used here to get optimized native instructions
> for port I/O in Linux be writing raw instruction strings. Adding a
> wrapper layer here is fairly easy, and makes the full range of I/O
> instructions available to the VMI interface.
> Also, slowing down I/O is not a useful operation in a VM, so there
> is a VMI call specifically to allow making it a NOP. I could find
> no place where SLOW_IO_BY_JUMPING is still used, and consider it
> obsoleted. Even on older 386 systems, the I/O delay approximation
> by touching the extra page register is likely to better.
This sounds like a prime candidate for the alternate instruction interfaces
and I don't see that being used here.
Xen-devel mailing list