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From: Nicolas Pitre <nicolas.pitre@linaro.org>
To: Dave Martin <dave.martin@linaro.org>
Cc: Richard Earnshaw <Richard.Earnshaw@arm.com>,
	"xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
	"linaro-dev@lists.linaro.org" <linaro-dev@lists.linaro.org>,
	Ian Campbell <Ian.Campbell@citrix.com>,
	"arnd@arndb.de" <arnd@arndb.de>,
	Catalin Marinas <Catalin.Marinas@arm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	David Vrabel <david.vrabel@citrix.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH-WIP 01/13] xen/arm: use r12 to pass the hypercall number to the hypervisor
Date: Fri, 9 Mar 2012 11:20:20 -0500 (EST)	[thread overview]
Message-ID: <alpine.LFD.2.02.1203091112050.24151@xanadu.home> (raw)
In-Reply-To: <CA+wbFdfF5c+Bw6RrxCm3YThqCRDuDYzanq+HV8a6LyXaBqWrQA@mail.gmail.com>

On Fri, 9 Mar 2012, Dave Martin wrote:

> Register variables feel like a red herring though.  We're only using
> those because we can't do the needful thing and actually desscribe
> these constraints in the asm constraints (which would seem to be the
> right place).  We specifically don't care where those values are
> except at the boundaries of the asm block itself.

Absolutely.

> Is there a reason why ARM gcc doesn't provide the ability to specify
> such exact-register constraints, or is this more for historical
> reasons?  It is possible?

I don't know how much things have changed since I last looked at the gcc 
code, but implementing this seemed to be pretty trivial at the time.  
The problem would be to determine a good letter scheme to map to actual 
registers.


Nicolas

  reply	other threads:[~2012-03-09 16:20 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-23 17:47 [PATCH-WIP 00/13] xen/arm: receive Xen events and initialize xenbus Stefano Stabellini
2012-02-23 17:48 ` [PATCH-WIP 01/13] xen/arm: use r12 to pass the hypercall number to the hypervisor Stefano Stabellini
2012-02-27 16:27   ` Ian Campbell
     [not found]     ` <1330360043.8557.302.camel-o4Be2W7LfRlXesXXhkcM7miJhflN2719@public.gmane.org>
2012-02-27 18:03       ` Dave Martin
2012-02-27 19:33         ` Ian Campbell
     [not found]           ` <1330371219.10008.34.camel-ztPmHsLffjjnO4AKDKe2m+kiAK3p4hvP@public.gmane.org>
2012-02-28 10:20             ` Dave Martin
2012-02-28 10:48               ` Ian Campbell
     [not found]                 ` <1330426133.31269.70.camel-o4Be2W7LfRlXesXXhkcM7miJhflN2719@public.gmane.org>
2012-02-28 12:28                   ` Stefano Stabellini
2012-02-29  9:34                     ` Dave Martin
2012-02-29  9:56                       ` Ian Campbell
2012-02-29 11:47                         ` Dave Martin
     [not found]                         ` <1330509362.4270.20.camel-o4Be2W7LfRlXesXXhkcM7miJhflN2719@public.gmane.org>
2012-02-29 12:58                           ` Dave Martin
2012-02-29 14:44                             ` Ian Campbell
     [not found]                               ` <1330526664.4270.128.camel-o4Be2W7LfRlXesXXhkcM7miJhflN2719@public.gmane.org>
2012-03-01  9:35                                 ` Dave Martin
2012-03-01 10:12                               ` Russell King - ARM Linux
2012-03-02 21:19                               ` Nicolas Pitre
2012-02-29 14:52                             ` Stefano Stabellini
2012-03-01  9:51                               ` Dave Martin
2012-03-01 10:10                             ` Russell King - ARM Linux
     [not found]                               ` <20120301101029.GB7363-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2012-03-01 10:27                                 ` Dave Martin
2012-03-01 10:35                                   ` Russell King - ARM Linux
     [not found]                                     ` <20120301103520.GD7363-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2012-03-01 12:12                                       ` Stefano Stabellini
     [not found]                             ` <20120229125826.GC2077-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
2012-03-02 21:15                               ` Nicolas Pitre
2012-03-08  9:58                                 ` Richard Earnshaw
2012-03-08 12:17                                   ` Dave Martin
2012-03-08 17:21                                   ` Nicolas Pitre
     [not found]                                     ` <alpine.LFD.2.02.1203081041340.24151-QuJgVwGFrdf/9pzu0YdTqQ@public.gmane.org>
2012-03-08 18:47                                       ` Richard Earnshaw
     [not found]                                         ` <4F58FEC0.8080706-5wv7dgnIgG8@public.gmane.org>
2012-03-09 15:58                                           ` Dave Martin
2012-03-09 16:20                                             ` Nicolas Pitre [this message]
     [not found]                                               ` <alpine.LFD.2.02.1203091112050.24151-QuJgVwGFrdf/9pzu0YdTqQ@public.gmane.org>
2012-03-09 17:38                                                 ` Richard Earnshaw
2012-02-27 21:05       ` Peter Maydell
2012-02-28 10:12         ` Ian Campbell
     [not found]   ` <1330019314-20865-1-git-send-email-stefano.stabellini-mvvWK6WmYclDPfheJLI6IQ@public.gmane.org>
2012-02-27 17:53     ` Dave Martin
2012-02-27 19:48       ` Ian Campbell
     [not found]         ` <1330372125.10008.47.camel-ztPmHsLffjjnO4AKDKe2m+kiAK3p4hvP@public.gmane.org>
2012-02-28  9:46           ` Dave Martin
2012-02-28 10:07             ` Ian Campbell
     [not found]             ` <20120228094616.GA2063-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
2012-02-28 12:21               ` Stefano Stabellini
2012-02-23 17:48 ` [PATCH-WIP 02/13] xen/arm: introduce privcmp, physdev_op and memory_op hypercalls Stefano Stabellini
2012-02-23 17:48 ` [PATCH-WIP 03/13] xen/arm: mmu.h and page.h related definitions Stefano Stabellini
2012-02-23 17:48 ` [PATCH-WIP 04/13] xen/arm: sync_bitops Stefano Stabellini
2012-02-23 17:48 ` [PATCH-WIP 05/13] xen/arm: empty implementation of grant_table arch specific functions Stefano Stabellini
2012-02-23 17:48 ` [PATCH-WIP 06/13] xen/arm: missing includes Stefano Stabellini
2012-02-23 17:48 ` [PATCH-WIP 07/13] xen/arm: receive xen events on arm Stefano Stabellini
2012-02-24 11:12   ` David Vrabel
     [not found]     ` <4F4770AD.6040703-Sxgqhf6Nn4DQT0dZR+AlfA@public.gmane.org>
2012-02-24 12:23       ` Stefano Stabellini
2012-02-23 17:48 ` [PATCH-WIP 08/13] xen/arm: fix arm xen guest handle definitions Stefano Stabellini
2012-02-23 17:48 ` [PATCH-WIP 09/13] xen/arm: shared_info and start_info Stefano Stabellini
2012-02-23 17:48 ` [PATCH-WIP 10/13] xen/arm: empty implementation of xen_remap_domain_mfn_range Stefano Stabellini
2012-02-23 17:48 ` [PATCH-WIP 11/13] xen/arm: Introduce xen_pfn_t for pfn and mfn types Stefano Stabellini
2012-02-23 17:48 ` [PATCH-WIP 12/13] xen/arm: compile and run xenbus Stefano Stabellini
2012-02-23 17:48 ` [PATCH-WIP 13/13] xen/arm: compile grant-table features events and xenbus, do not compile pci Stefano Stabellini

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