* SDIV / UDIV Question
@ 2013-10-09 7:08 Wang, Yalin
2013-10-09 10:53 ` Will Deacon
0 siblings, 1 reply; 4+ messages in thread
From: Wang, Yalin @ 2013-10-09 7:08 UTC (permalink / raw)
To: 'Will Deacon'
Cc: 'linux-arm-msm-owner@vger.kernel.org', linux-kernel
Hi Will
I have a question about sdiv/ udiv instructions :
In armv7 A/R TRM, it said sdiv/udiv will cause
Divide by zero as undefined exception or just return zero
(decided by implementation) .
So in kernel , should we need register a undef hook to
Get this undef exception and send SIGFPE to user space
Process ?
Thanks
Yalin.Wang
Software Engineer
OS Kernel&Graphics
Sony Mobile Communications
Tel: +86 10 5966 9819
Phone: 18610323092
Address: No.16 Guangshun South Street, Chaoyang, Beijing, P.R.C.
sonymobile.com
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: SDIV / UDIV Question
2013-10-09 7:08 SDIV / UDIV Question Wang, Yalin
@ 2013-10-09 10:53 ` Will Deacon
2013-10-10 5:04 ` Wang, Yalin
0 siblings, 1 reply; 4+ messages in thread
From: Will Deacon @ 2013-10-09 10:53 UTC (permalink / raw)
To: Wang, Yalin; +Cc: 'linux-arm-msm-owner@vger.kernel.org', linux-kernel
On Wed, Oct 09, 2013 at 08:08:05AM +0100, Wang, Yalin wrote:
> I have a question about sdiv/ udiv instructions :
> In armv7 A/R TRM, it said sdiv/udiv will cause
> Divide by zero as undefined exception or just return zero
> (decided by implementation) .
>
> So in kernel , should we need register a undef hook to
> Get this undef exception and send SIGFPE to user space
> Process ?
As far as I can see, this can only happen for R-class cores,
based on SCTLR.DZ.
Will
^ permalink raw reply [flat|nested] 4+ messages in thread
* RE: SDIV / UDIV Question
2013-10-09 10:53 ` Will Deacon
@ 2013-10-10 5:04 ` Wang, Yalin
2013-10-10 9:21 ` Will Deacon
0 siblings, 1 reply; 4+ messages in thread
From: Wang, Yalin @ 2013-10-10 5:04 UTC (permalink / raw)
To: 'Will Deacon'
Cc: 'linux-arm-msm-owner@vger.kernel.org', linux-kernel
Hi Will ,
Oh , I see ,
Thanks for your clarification !
So R-class cores will not run linux ?
This means we don't need care about this .
Am I right ?
Thank you .
-----Original Message-----
From: Will Deacon [mailto:will.deacon@arm.com]
Sent: Wednesday, October 09, 2013 6:54 PM
To: Wang, Yalin
Cc: 'linux-arm-msm-owner@vger.kernel.org'; linux-kernel@vger.kernel.org
Subject: Re: SDIV / UDIV Question
On Wed, Oct 09, 2013 at 08:08:05AM +0100, Wang, Yalin wrote:
> I have a question about sdiv/ udiv instructions :
> In armv7 A/R TRM, it said sdiv/udiv will cause Divide by zero as
> undefined exception or just return zero (decided by implementation) .
>
> So in kernel , should we need register a undef hook to Get this
> undef exception and send SIGFPE to user space Process ?
As far as I can see, this can only happen for R-class cores, based on SCTLR.DZ.
Will
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: SDIV / UDIV Question
2013-10-10 5:04 ` Wang, Yalin
@ 2013-10-10 9:21 ` Will Deacon
0 siblings, 0 replies; 4+ messages in thread
From: Will Deacon @ 2013-10-10 9:21 UTC (permalink / raw)
To: Wang, Yalin
Cc: 'linux-arm-msm-owner@vger.kernel.org',
linux-kernel, jonathan.austin
[Adding Jonny]
On Thu, Oct 10, 2013 at 06:04:41AM +0100, Wang, Yalin wrote:
> Oh , I see ,
> Thanks for your clarification !
> So R-class cores will not run linux ?
R-class cores can run Linux, but I don't reckon we touch SCTLR.DZ. I've
added Jonny, so he can clarify the behaviour here. (I'm also not sure which
cores have these instructions either).
Will
> -----Original Message-----
> From: Will Deacon [mailto:will.deacon@arm.com]
> Sent: Wednesday, October 09, 2013 6:54 PM
> To: Wang, Yalin
> Cc: 'linux-arm-msm-owner@vger.kernel.org'; linux-kernel@vger.kernel.org
> Subject: Re: SDIV / UDIV Question
>
> On Wed, Oct 09, 2013 at 08:08:05AM +0100, Wang, Yalin wrote:
> > I have a question about sdiv/ udiv instructions :
> > In armv7 A/R TRM, it said sdiv/udiv will cause Divide by zero as
> > undefined exception or just return zero (decided by implementation) .
> >
> > So in kernel , should we need register a undef hook to Get this
> > undef exception and send SIGFPE to user space Process ?
>
> As far as I can see, this can only happen for R-class cores, based on SCTLR.DZ.
>
> Will
>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2013-10-10 9:21 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2013-10-09 7:08 SDIV / UDIV Question Wang, Yalin
2013-10-09 10:53 ` Will Deacon
2013-10-10 5:04 ` Wang, Yalin
2013-10-10 9:21 ` Will Deacon
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®