Re: [PATCH v6] eal/x86: add 128-bit atomic compare exchange

From: "Eads, Gage" <gage.eads@intel.com>
To: Thomas Monjalon <thomas@monjalon.net>,
	"Yigit, Ferruh" <ferruh.yigit@intel.com>
Cc: Shahaf Shuler <shahafs@mellanox.com>,
	Matan Azrad <matan@mellanox.com>,
	Yongseok Koh <yskoh@mellanox.com>, "dev@dpdk.org" <dev@dpdk.org>,
	"olivier.matz@6wind.com" <olivier.matz@6wind.com>,
	"arybchenko@solarflare.com" <arybchenko@solarflare.com>,
	"Richardson, Bruce" <bruce.richardson@intel.com>,
	"Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
	"gavin.hu@arm.com" <gavin.hu@arm.com>,
	"Honnappa.Nagarahalli@arm.com" <Honnappa.Nagarahalli@arm.com>,
	"nd@arm.com" <nd@arm.com>,
	"chaozhu@linux.vnet.ibm.com" <chaozhu@linux.vnet.ibm.com>,
	"jerinj@marvell.com" <jerinj@marvell.com>,
	"hemant.agrawal@nxp.com" <hemant.agrawal@nxp.com>
Subject: Re: [PATCH v6] eal/x86: add 128-bit atomic compare exchange
Date: Thu, 4 Apr 2019 12:24:51 +0000	[thread overview]
Message-ID: <9184057F7FC11744A2107296B6B8EB1E54210CEA@FMSMSX108.amr.corp.intel.com> (raw)
In-Reply-To: 2748440.W4LoRDhJ5f@xps

> -----Original Message-----
> From: Eads, Gage
> Sent: Thursday, April 4, 2019 7:23 AM
> To: 'Thomas Monjalon' <thomas@monjalon.net>; Yigit, Ferruh
> <ferruh.yigit@intel.com>
> Cc: Shahaf Shuler <shahafs@mellanox.com>; Matan Azrad
> <matan@mellanox.com>; Yongseok Koh <yskoh@mellanox.com>;
> dev@dpdk.org; olivier.matz@6wind.com; arybchenko@solarflare.com;
> Richardson, Bruce <bruce.richardson@intel.com>; Ananyev, Konstantin
> <konstantin.ananyev@intel.com>; gavin.hu@arm.com;
> Honnappa.Nagarahalli@arm.com; nd@arm.com;
> chaozhu@linux.vnet.ibm.com; jerinj@marvell.com;
> hemant.agrawal@nxp.com
> Subject: RE: [dpdk-dev] [PATCH v6] eal/x86: add 128-bit atomic compare
> exchange
> 
> > -----Original Message-----
> > From: Thomas Monjalon [mailto:thomas@monjalon.net]
> > Sent: Thursday, April 4, 2019 7:18 AM
> > To: Eads, Gage <gage.eads@intel.com>; Yigit, Ferruh
> > <ferruh.yigit@intel.com>
> > Cc: Shahaf Shuler <shahafs@mellanox.com>; Matan Azrad
> > <matan@mellanox.com>; Yongseok Koh <yskoh@mellanox.com>;
> dev@dpdk.org;
> > olivier.matz@6wind.com; arybchenko@solarflare.com; Richardson, Bruce
> > <bruce.richardson@intel.com>; Ananyev, Konstantin
> > <konstantin.ananyev@intel.com>; gavin.hu@arm.com;
> > Honnappa.Nagarahalli@arm.com; nd@arm.com;
> chaozhu@linux.vnet.ibm.com;
> > jerinj@marvell.com; hemant.agrawal@nxp.com
> > Subject: Re: [dpdk-dev] [PATCH v6] eal/x86: add 128-bit atomic compare
> > exchange
> >
> > 04/04/2019 14:14, Eads, Gage:
> > > From: Thomas Monjalon [mailto:thomas@monjalon.net]
> > > > 04/04/2019 14:08, Thomas Monjalon:
> > > > > 04/04/2019 13:47, Ferruh Yigit:
> > > > > > .../dpdk/x86_64-native-linuxapp-
> gcc/include/rte_atomic_64.h:223:3:
> > > > > > error: ISO C does not support ‘__int128’ types
> > > > > > [-Werror=pedantic]
> > > > >
> > > > > We can try this kind of workaround (disable pedantic locally):
> > > > >
> > > >
> >
> https://github.com/HowardHinnant/date/pull/38/commits/177032852d5b46
> > > > 14
> > > > > 112ca1ab3ef42d6b41824816
> > > >
> > > > Or better:
> > > > __extension__ typedef __int128 int128;
> > > >
> > >
> > > Taking that one step further -- RTE_STD_C11 evaluates to
> > > __extension__
> > (when the STD C version is sufficiently old).
> >
> > I don't think __int128 is part of C11. Is it?
> 
> You're right, this is a compiler extension. Using '__extension__' makes more
> sense.

FYI, __int128 was added in GCC 4.6 (and DPDK's minimum version is currently 4.9).