linux-kernel - Re: Xen is a feature

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <alpine.LFD.2.00.0906032204220.3419@localhost.localdomain>
Date:	Wed, 3 Jun 2009 22:20:02 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Bill Davidsen <davidsen@....com>
cc:	George Dunlap <george.dunlap@...citrix.com>,
	David Miller <davem@...emloft.net>,
	"jeremy@...p.org" <jeremy@...p.org>,
	"mingo@...e.hu" <mingo@...e.hu>,
	Dan Magenheimer <dan.magenheimer@...cle.com>,
	"avi@...hat.com" <avi@...hat.com>,
	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Keir Fraser <Keir.Fraser@...citrix.com>,
	"torvalds@...ux-foundation.org" <torvalds@...ux-foundation.org>,
	"gregkh@...e.de" <gregkh@...e.de>,
	"kurt.hackel@...cle.com" <kurt.hackel@...cle.com>,
	Ian Pratt <Ian.Pratt@...citrix.com>,
	"xen-users@...ts.xensource.com" <xen-users@...ts.xensource.com>,
	ksrinivasan <ksrinivasan@...ell.com>,
	"EAnderson@...ell.com" <EAnderson@...ell.com>,
	"wimcoekaerts@...mekes.net" <wimcoekaerts@...mekes.net>,
	Stephen Spector <stephen.spector@...rix.com>,
	jens.axboe@...cle.com
Subject: Re: Xen is a feature

On Wed, 3 Jun 2009, Bill Davidsen wrote:
> Thomas Gleixner wrote:
> > Aside of the paravirt, which seems to expand through arch/x86 like a
> > hydra, the new patches sprinkle "if (xen_...)" all over the
> > place. These extra xen dependencies are no improvement, they are a
> > royal pain in the ... They are sticky once they got merged simply
> > because the hypervisor relies on them and we need to provide
> > compatibility for a long time.
> > 
> Wait, let's not classify something as "no improvement" when you mean "I don't
> need it."

It's not about "I don't need it.". It's about having Xen dependencies
in the code all over the place which make mainatainence harder. I have
to balance the users benefit (xen dom0 support) vs. the impact on
maintainability and the restrictions which are going to be set almost
in stone by merging it.

> Let's stick to technical issues, and not deny that there are a number of users
> who really will have expanded capability. The technical points are valid, but
> as a former and probable future xen (CentOS) user, so are the benefits.

Refusing random "if (xen...)" dependencies is a purely technical
decision. I have said more than once that I'm not against merging dom0
in general, I'm just frightened by the technical impact of a defacto
ABI which we swallow with it.

We have enough problems with real silicon and BIOS/ACPI already, why
should we add artifical and _avoidable_ virtual silicon horror ?

Thanks,

	tglx
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/