Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752744AbaKXM6q (ORCPT ); Mon, 24 Nov 2014 07:58:46 -0500 Received: from mail-la0-f42.google.com ([209.85.215.42]:52237 "EHLO mail-la0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751078AbaKXM6o (ORCPT ); Mon, 24 Nov 2014 07:58:44 -0500 MIME-Version: 1.0 In-Reply-To: <20141124121503.GB14353@redhat.com> References: <1416829787-14252-1-git-send-email-mst@redhat.com> <1416829787-14252-5-git-send-email-mst@redhat.com> <20141124121503.GB14353@redhat.com> Date: Mon, 24 Nov 2014 13:58:43 +0100 X-Google-Sender-Auth: NA8ooCuYEuEXVexzwi0aTFxJASo Message-ID: Subject: Re: [PATCH v3 04/41] virtio: memory access APIs From: Geert Uytterhoeven To: "Michael S. Tsirkin" Cc: "linux-kernel@vger.kernel.org" , David Miller , cornelia.huck@de.ibm.com, rusty@au1.ibm.com, Nicholas Bellinger , Paolo Bonzini , Rusty Russell , Greg Kroah-Hartman , Alexei Starovoitov , Pranavkumar Sawargaonkar , Anup Patel , Sakari Ailus , Bjarke Istrup Pedersen , stephen hemminger , virtualization@lists.linux-foundation.org, linux-api@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 24, 2014 at 1:15 PM, Michael S. Tsirkin wrote: > On Mon, Nov 24, 2014 at 01:03:24PM +0100, Geert Uytterhoeven wrote: >> On Mon, Nov 24, 2014 at 12:52 PM, Michael S. Tsirkin wrote: >> > virtio 1.0 makes all memory structures LE, so >> > we need APIs to conditionally do a byteswap on BE >> > architectures. >> > >> > To make it easier to check code statically, >> > add virtio specific types for multi-byte integers >> > in memory. >> > >> > Add low level wrappers that do a byteswap conditionally, these will be >> > useful e.g. for vhost. Add high level wrappers that >> > query device endian-ness and act accordingly. >> >> > diff --git a/include/linux/virtio_byteorder.h b/include/linux/virtio_byteorder.h >> > new file mode 100644 >> > index 0000000..824ed0b >> > --- /dev/null >> > +++ b/include/linux/virtio_byteorder.h >> >> > +static inline u16 __virtio16_to_cpu(bool little_endian, __virtio16 val) >> > +{ >> > + if (little_endian) >> > + return le16_to_cpu((__force __le16)val); >> > + else >> > + return (__force u16)val; >> > +} >> >> What's wrong with just using le16-to_cpu() ... > > le16-to_cpu() is simply wrong: virtio needs to be > LE or native endian, depending on whether it's running > in 0.9 or 1.0 mode. IC, that was not clear from the description for this patch. I thought it was dependent on BE architectures. Nevertheless, any chance you can get rid of the "conditional"? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/