From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Ian Campbell <Ian.Campbell@citrix.com>
Cc: Dave Martin <dave.martin@linaro.org>,
Peter Maydell <peter.maydell@linaro.org>,
"xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
"linaro-dev@lists.linaro.org" <linaro-dev@lists.linaro.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"arnd@arndb.de" <arnd@arndb.de>,
Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>,
"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
David Vrabel <david.vrabel@citrix.com>,
"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: Thu, 1 Mar 2012 10:12:58 +0000 [thread overview]
Message-ID: <20120301101258.GC7363@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <1330526664.4270.128.camel@zakaz.uk.xensource.com>
On Wed, Feb 29, 2012 at 02:44:24PM +0000, Ian Campbell wrote:
> > If you need a specific register, this means that you must set up that
> > register explicitly inside the asm if you want a guarantee that the
> > code will work:
> >
> > asm volatile (
> > "movw r12, %[hvc_num]\n\t"
>
> Is gcc (or gas?) smart enough to optimise this away if it turns out that
> %[hvc_num] == r12?
No, and it won't do, because %[hvc_num] is specified in these operands:
> > ...
> > "hvc #0"
> > :: [hvc_num] "i" (NUMBER) : "r12"
to be an integer, not a register.
> How are system calls implemented on the userspace side? I confess I
> don't know what the ARM syscall ABI looks like -- is it all registers or
> is some of it on the stack? It sounds like the solution ought to be
> pretty similar though.
All registers. We have a few which take a pointer to an in memory array,
but those are for some old multiplexed syscalls.
next prev parent reply other threads:[~2012-03-01 10:12 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 [this message]
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
[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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