From: Robert Richter <robert.richter@caviumnetworks.com>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: Robert Richter <rric@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Jason Cooper <jason@lakedaemon.net>,
Marc Zyngier <marc.zyngier@arm.com>,
<linux-kernel@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] GICv3: Fixing 32 bit compatibility
Date: Tue, 9 Sep 2014 11:26:53 +0200 [thread overview]
Message-ID: <20140909092653.GC4588@rric.localhost> (raw)
In-Reply-To: <20140909091912.GQ23009@pengutronix.de>
On 09.09.14 11:19:12, Uwe Kleine-König wrote:
> On Tue, Sep 09, 2014 at 11:12:01AM +0200, Robert Richter wrote:
> > On 09.09.14 10:00:42, Uwe Kleine-König wrote:
> > > On Mon, Sep 08, 2014 at 04:11:19PM +0200, Robert Richter wrote:
> >
> > > > @@ -479,7 +479,7 @@ static void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
> > > > smp_wmb();
> > > >
> > > > for_each_cpu_mask(cpu, *mask) {
> > > > - u64 cluster_id = cpu_logical_map(cpu) & ~0xffUL;
> > > > + u64 cluster_id = cpu_logical_map(cpu) & ~0xffULL;
> > > This doesn't change anything, does it?
> >
> > It does, not in 64 bit but in 32 bit there unsigned long is 32
> > bit. So, bit masks are broken if you compile a 32 bit kernel.
> Can you make an example where the result actually changes?
Upper 32 bits will be cleared above.
> > > I wonder if it would be cleaner to use (u64)0xff here.
> >
> > No, that's ULL for. This is commonly used in x86 too.
> I don't care much here, but I'd say ULL is to force an unsigned long
> long. If you want to make it obvious that you want a 64bit value, a cast
> to u64 makes this more clear.
ULL is no cast at all.
-Robert
next prev parent reply other threads:[~2014-09-09 11:02 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-08 14:11 [PATCH] GICv3: Fixing 32 bit compatibility Robert Richter
2014-09-08 14:24 ` Marc Zyngier
2014-09-14 5:55 ` Jason Cooper
2014-09-08 14:31 ` [PATCH] ITS: " Robert Richter
2014-09-09 8:00 ` [PATCH] GICv3: " Uwe Kleine-König
2014-09-09 9:12 ` Robert Richter
2014-09-09 9:19 ` Uwe Kleine-König
2014-09-09 9:26 ` Robert Richter [this message]
2014-09-09 9:43 ` Uwe Kleine-König
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