From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pawel Moll Subject: Re: [PATCH] virtio-spec: Define virtio-mmio registers as LE Date: Wed, 06 Mar 2013 15:10:15 +0000 Message-ID: <1362582615.3105.45.camel@hornet> References: <87wqubkalj.fsf@rustcorp.com.au> <1360839247-9131-1-git-send-email-pawel.moll@arm.com> <513085EA.8070007@arm.com> <1362135005.3052.26.camel@hornet> <51308F22.7040303@arm.com> <1362141432.3052.28.camel@hornet> <87fw0ad7sr.fsf@rustcorp.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <87fw0ad7sr.fsf@rustcorp.com.au> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Rusty Russell Cc: "Michael S. Tsirkin" , "linux-kernel@vger.kernel.org" , "virtualization@lists.linux-foundation.org" List-Id: virtualization@lists.linuxfoundation.org T24gVHVlLCAyMDEzLTAzLTA1IGF0IDAwOjExICswMDAwLCBSdXN0eSBSdXNzZWxsIHdyb3RlOgo+ IFBhd2VsIE1vbGwgPHBhd2VsLm1vbGxAYXJtLmNvbT4gd3JpdGVzOgo+ID4gT24gRnJpLCAyMDEz LTAzLTAxIGF0IDExOjIxICswMDAwLCBNYXJjIFp5bmdpZXIgd3JvdGU6Cj4gPj4gPiBIYXZpbmcg c2FpZCB0aGF0LCBSdXN0eSB3YXMgY29udGVtcGxhdGluZyBlbmZvcmNpbmcgTEUgY29uZmlnIHNw YWNlIGluCj4gPj4gPiB0aGUgbmV3IFBDSSBsYXlvdXQuLi4KPiA+PiAKPiA+PiBJIHdvdWxkbid0 IGNvbXBsYWluIGFib3V0IHRoYXQsIGFuZCB3b3VsZCBsaWtlIHRvIHNlZSBhIHNpbWlsYXIgdGhp bmcgb24KPiA+PiBNTUlPLgo+ID4KPiA+IFdoZXJldmVyIFBDSSBnb2VzLCBNTUlPIGZvbGxvd3Mg Oi0pCj4gCj4gWWVzLCBidXQgaWYgeW91IHN3aXRjaCBmcm9tICdndWVzdC1lbmRpYW4nIHRvICds aXR0bGUtZW5kaWFuJyBob3cgd2lsbAo+IHlvdSB0ZWxsPyAgRm9yIFBDSSwgd2UnZCBkZXRlY3Qg aXQgYnkgdXNpbmcgdGhlIG5ldyBsYXlvdXQuCgpUaGUgdmVyc2lvbiByZWdpc3Rlci92YWx1ZS4g QXQgc29tZSBwb2ludCBvZiB0aW1lIHRoZXJlIHdpbGwgYmUgYQpuZXcoaXNoKSBNTUlPIGxheW91 dCBhbnl3YXkgdG8gZGVhbCB3aXRoIDY0LWJpdCBhZGRyZXNzZXMsIHJlcGxhY2luZyB0aGUKcmlu ZyBwYWdlIG51bWJlciB3aXRoIHR3byAzMi1iaXQgaGkvbG8gcGh5c2ljYWwgYWRkcmVzcyByZWdp c3RlcnMuIFRoaXMKd2FzIGRpc2N1c3NlZCBub3QgbG9uZyBhZnRlciB0aGUgZHJpdmVyIGdvdCBt ZXJnZWQuLi4KCj4gSSdkIHJhdGhlciB5b3Ugc3BlY2lmeSBNTUlPIGFzIGxpdHRsZSBlbmRpYW4s IGFuZCB3ZSBmaXggdGhlIGtlcm5lbAo+IGNvbmZpZyBhY2Nlc3NvcnMgdG8gYmUgZW5kaWFuIGF3 YXJlIChpZS4gOCwgMTYsIDMyLCA2NC1iaXQgYWNjZXNzb3JzKS4KPiBTaW5jZSBub29uZSBCRSBp cyB1c2luZyBNTUlPIHJpZ2h0IG5vdywgaXQncyBzYWZlLi4uCgpUaGF0J3MgYWJzb2x1dGVseSBm aW5lIHdpdGggbWUsIGhvd2V2ZXIgSSBkb24ndCBzZWUgYW55dGhpbmcgSSBjb3VsZCBkbwppbiB0 aGUgdmlydGlvX21taW8gZHJpdmVyIGFuZCBzcGVjIC0gdGhlIHZpcnRpb19jb25maWdfb3BzIHNw ZWNpZmllcwpnZXQvc2V0IGFzIHZvaWQgKiBvcGVyYXRpb25zIGFuZCBJIHNpbXBseSBkbyBieXRl LWJ5LWJ5dGUgY29weS4gSGF2ZSBJCm1pc3NlZCBzb21lIGNvbmZpZy9lbmRpYW5lc3MvUENJIHJl bGF0ZWQgZGlzY3Vzc2lvbj8KClBhd2XFggoKCl9fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fClZpcnR1YWxpemF0aW9uIG1haWxpbmcgbGlzdApWaXJ0dWFsaXph dGlvbkBsaXN0cy5saW51eC1mb3VuZGF0aW9uLm9yZwpodHRwczovL2xpc3RzLmxpbnV4Zm91bmRh dGlvbi5vcmcvbWFpbG1hbi9saXN0aW5mby92aXJ0dWFsaXphdGlvbg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758118Ab3CFPKV (ORCPT ); Wed, 6 Mar 2013 10:10:21 -0500 Received: from service87.mimecast.com ([91.220.42.44]:46629 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757137Ab3CFPKU convert rfc822-to-8bit (ORCPT ); Wed, 6 Mar 2013 10:10:20 -0500 Message-ID: <1362582615.3105.45.camel@hornet> Subject: Re: [PATCH] virtio-spec: Define virtio-mmio registers as LE From: Pawel Moll To: Rusty Russell Cc: Marc Zyngier , "virtualization@lists.linux-foundation.org" , "linux-kernel@vger.kernel.org" , "Michael S. Tsirkin" Date: Wed, 06 Mar 2013 15:10:15 +0000 In-Reply-To: <87fw0ad7sr.fsf@rustcorp.com.au> References: <87wqubkalj.fsf@rustcorp.com.au> <1360839247-9131-1-git-send-email-pawel.moll@arm.com> <513085EA.8070007@arm.com> <1362135005.3052.26.camel@hornet> <51308F22.7040303@arm.com> <1362141432.3052.28.camel@hornet> <87fw0ad7sr.fsf@rustcorp.com.au> X-Mailer: Evolution 3.6.2-0ubuntu0.1 Mime-Version: 1.0 X-OriginalArrivalTime: 06 Mar 2013 15:10:15.0714 (UTC) FILETIME=[B51C9820:01CE1A7C] X-MC-Unique: 113030615101731401 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2013-03-05 at 00:11 +0000, Rusty Russell wrote: > Pawel Moll writes: > > On Fri, 2013-03-01 at 11:21 +0000, Marc Zyngier wrote: > >> > Having said that, Rusty was contemplating enforcing LE config space in > >> > the new PCI layout... > >> > >> I wouldn't complain about that, and would like to see a similar thing on > >> MMIO. > > > > Wherever PCI goes, MMIO follows :-) > > Yes, but if you switch from 'guest-endian' to 'little-endian' how will > you tell? For PCI, we'd detect it by using the new layout. The version register/value. At some point of time there will be a new(ish) MMIO layout anyway to deal with 64-bit addresses, replacing the ring page number with two 32-bit hi/lo physical address registers. This was discussed not long after the driver got merged... > I'd rather you specify MMIO as little endian, and we fix the kernel > config accessors to be endian aware (ie. 8, 16, 32, 64-bit accessors). > Since noone BE is using MMIO right now, it's safe... That's absolutely fine with me, however I don't see anything I could do in the virtio_mmio driver and spec - the virtio_config_ops specifies get/set as void * operations and I simply do byte-by-byte copy. Have I missed some config/endianess/PCI related discussion? Paweł