From: Peter Zijlstra <peterz@infradead.org>
To: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
Jeremy Fitzhardinge <jeremy@goop.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
Xen Devel <Xen-devel@lists.xensource.com>,
Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
"H. Peter Anvin" <hpa@zytor.com>,
linux-next@vger.kernel.org, linux-kernel@vger.kernel.org,
Andy Lutomirski <luto@kernel.org>,
David Vrabel <david.vrabel@citrix.com>
Subject: Re: linux-next: manual merge of the xen-tip tree with the tip tree
Date: Wed, 12 Aug 2015 19:38:23 +0200 [thread overview]
Message-ID: <20150812173823.GG18673@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20150812172105.GW16853@twins.programming.kicks-ass.net>
On Wed, Aug 12, 2015 at 07:21:05PM +0200, Peter Zijlstra wrote:
> On Wed, Aug 12, 2015 at 09:27:38AM -0400, Boris Ostrovsky wrote:
>
> > Incidentally, 11276d53 ("locking/static_keys: Add a new static_key
> > interface") breaks old-ish compilers (gcc version 4.4.4 20100503 (Red Hat
> > 4.4.4-2) (GCC)):
> >
> >
> >
> > CC arch/x86/kernel/nmi.o
> > In file included from
> > /home/build/linux-boris/include/linux/jump_label.h:109,
> > from
> > /home/build/linux-boris/arch/x86/include/asm/spinlock.h:5,
> > from /home/build/linux-boris/include/linux/spinlock.h:88,
> > from /home/build/linux-boris/arch/x86/kernel/nmi.c:14:
> > /home/build/linux-boris/arch/x86/include/asm/jump_label.h: In function
> > ‘nmi_handle’:
> > /home/build/linux-boris/arch/x86/include/asm/jump_label.h:21: warning: asm
> > operand 0 probably doesn’t match constraints
> > /home/build/linux-boris/arch/x86/include/asm/jump_label.h:21: error:
> > impossible constraint in ‘asm’
> > make[3]: *** [arch/x86/kernel/nmi.o] Error 1
> > make[2]: *** [arch/x86/kernel] Error 2
> > make[1]: *** [arch/x86] Error 2
>
> Ugh bugger.
>
> I bet its that: &((char *)key)[branch] business, an earlier variant
> thereof tripped up more recent GCCs too.
>
> So its an __always_inline function, and both argument are always compile
> time constants, @key is the address of an object in static storage (a
> global) and @branch is a simple 0/1 at the call site.
>
> Now we wish to compute (unsigned long)key + branch at compile/link time
> to feed to the assembler as an immediate, which should be possible,
> given its all 'constants'.
>
> It just appears GCC is having a hard time with this.
>
> Let me see if I have a sufficiently old GCC around to play with.
So both my 4.4 compilers:
gcc-4.4 (Ubuntu/Linaro 4.4.7-8ubuntu1) 4.4.7
gcc-4.4 (Debian 4.4.7-2) 4.4.7
Do not have CC_HAVE_ASM_GOTO at all, and my gcc-4.6 (my next oldest
compiler) doesn't have trouble building this.
next prev parent reply other threads:[~2015-08-12 17:38 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-12 5:09 linux-next: manual merge of the xen-tip tree with the tip tree Stephen Rothwell
2015-08-12 13:27 ` Boris Ostrovsky
2015-08-12 17:21 ` Peter Zijlstra
2015-08-12 17:38 ` Peter Zijlstra [this message]
2015-08-12 17:46 ` Peter Zijlstra
2015-08-12 18:17 ` Boris Ostrovsky
2015-08-12 18:26 ` Andy Lutomirski
2015-08-12 18:30 ` Boris Ostrovsky
2015-08-12 18:26 ` H. Peter Anvin
2015-08-12 18:36 ` Peter Zijlstra
2015-08-12 18:44 ` Boris Ostrovsky
2015-08-12 19:04 ` Peter Zijlstra
2015-08-13 6:45 ` Ingo Molnar
-- strict thread matches above, loose matches on Subject: below --
2021-10-28 6:16 Stephen Rothwell
2017-08-31 4:37 Stephen Rothwell
2017-08-31 4:26 Stephen Rothwell
2017-08-31 8:10 ` Thomas Gleixner
2017-08-31 9:00 ` Thomas Gleixner
2017-08-31 9:16 ` Ingo Molnar
2017-08-31 12:36 ` Joe Perches
2017-08-31 10:11 ` Juergen Gross
2017-08-31 12:00 ` Thomas Gleixner
2017-08-31 14:01 ` Boris Ostrovsky
2017-08-31 14:03 ` Juergen Gross
2017-08-31 18:30 ` Thomas Gleixner
2017-08-28 5:20 Stephen Rothwell
2017-08-17 4:03 Stephen Rothwell
2017-06-28 4:21 Stephen Rothwell
2017-04-12 4:30 Stephen Rothwell
2017-04-26 4:57 ` Stephen Rothwell
2017-04-12 4:20 Stephen Rothwell
2017-03-29 3:36 Stephen Rothwell
2017-03-29 3:37 ` Stephen Rothwell
2017-03-29 3:35 Stephen Rothwell
2017-03-29 8:37 ` Juergen Gross
2017-03-29 8:59 ` Ingo Molnar
2017-03-29 9:28 ` Juergen Gross
2017-03-29 10:06 ` Vitaly Kuznetsov
2017-04-03 14:38 ` Ingo Molnar
2017-04-03 14:55 ` Juergen Gross
2017-03-29 9:54 ` Juergen Gross
2017-03-29 10:41 ` Ingo Molnar
2017-03-29 11:13 ` Stephen Rothwell
2016-10-03 1:29 Stephen Rothwell
2016-07-26 4:02 Stephen Rothwell
2016-07-26 4:01 Stephen Rothwell
2016-07-26 13:58 ` Boris Ostrovsky
2016-07-18 6:17 Stephen Rothwell
2016-05-02 4:51 Stephen Rothwell
2016-04-29 4:20 Stephen Rothwell
2014-03-20 4:15 Stephen Rothwell
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