From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754862AbeDWMKl (ORCPT ); Mon, 23 Apr 2018 08:10:41 -0400 Received: from mail-lf0-f67.google.com ([209.85.215.67]:36777 "EHLO mail-lf0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754746AbeDWMKj (ORCPT ); Mon, 23 Apr 2018 08:10:39 -0400 X-Google-Smtp-Source: AB8JxZogZxTtBG5cwhvBPNaCOFDvFpUuhjCY7LbRmf4uKgUvLn6srunA+UcB/pE4tUlznMCk2C7gmQ== Subject: Re: [Xen-devel] [PATCH 0/1] drm/xen-zcopy: Add Xen zero-copy helper DRM driver To: Wei Liu Cc: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , jgross@suse.com, Artem Mygaiev , Dongwon Kim , konrad.wilk@oracle.com, airlied@linux.ie, "Oleksandr_Andrushchenko@epam.com" , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, "Potrola, MateuszX" , xen-devel@lists.xenproject.org, daniel.vetter@intel.com, boris.ostrovsky@oracle.com References: <5d8fec7f-956c-378f-be90-f45029385740@gmail.com> <20180416192905.GA18096@downor-Z87X-UD5H> <20180417075928.GT31310@phenom.ffwll.local> <20180417205744.GA15930@downor-Z87X-UD5H> <41487acb-a67a-8933-d0c3-702c19b0938e@gmail.com> <20180418073508.ptvntwedczpvl7bx@MacBook-Pro-de-Roger.local> <20180418101058.hyqk3gr3b2ibxswu@MacBook-Pro-de-Roger.local> <20180420071914.GG31310@phenom.ffwll.local> <76cdc65a-7bb1-9377-7bc5-6164e32f7b5d@gmail.com> <20180423115242.ywdwqblj2aseu3fr@citrix.com> From: Oleksandr Andrushchenko Message-ID: <61105351-8896-072b-abf0-757c7f6c0edf@gmail.com> Date: Mon, 23 Apr 2018 15:10:35 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180423115242.ywdwqblj2aseu3fr@citrix.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/23/2018 02:52 PM, Wei Liu wrote: > On Fri, Apr 20, 2018 at 02:25:20PM +0300, Oleksandr Andrushchenko wrote: >>>> the gntdev. >>>> >>>> I think this is generic enough that it could be implemented by a >>>> device not tied to Xen. AFAICT the hyper_dma guys also wanted >>>> something similar to this. >>> You can't just wrap random userspace memory into a dma-buf. We've just had >>> this discussion with kvm/qemu folks, who proposed just that, and after a >>> bit of discussion they'll now try to have a driver which just wraps a >>> memfd into a dma-buf. >> So, we have to decide either we introduce a new driver >> (say, under drivers/xen/xen-dma-buf) or extend the existing >> gntdev/balloon to support dma-buf use-cases. >> >> Can anybody from Xen community express their preference here? >> > Oleksandr talked to me on IRC about this, he said a few IOCTLs need to > be added to either existing drivers or a new driver. > > I went through this thread twice and skimmed through the relevant > documents, but I couldn't see any obvious pros and cons for either > approach. So I don't really have an opinion on this. > > But, assuming if implemented in existing drivers, those IOCTLs need to > be added to different drivers, which means userspace program needs to > write more code and get more handles, it would be slightly better to > implement a new driver from that perspective. If gntdev/balloon extension is still considered: All the IOCTLs will be in gntdev driver (in current xen-zcopy terminology):  - DRM_ICOTL_XEN_ZCOPY_DUMB_FROM_REFS  - DRM_IOCTL_XEN_ZCOPY_DUMB_TO_REFS  - DRM_IOCTL_XEN_ZCOPY_DUMB_WAIT_FREE Balloon driver extension, which is needed for contiguous/DMA buffers, will be to provide new *kernel API*, no UAPI is needed. > Wei. Thank you, Oleksandr From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oleksandr Andrushchenko Subject: Re: [Xen-devel] [PATCH 0/1] drm/xen-zcopy: Add Xen zero-copy helper DRM driver Date: Mon, 23 Apr 2018 15:10:35 +0300 Message-ID: <61105351-8896-072b-abf0-757c7f6c0edf@gmail.com> References: <5d8fec7f-956c-378f-be90-f45029385740@gmail.com> <20180416192905.GA18096@downor-Z87X-UD5H> <20180417075928.GT31310@phenom.ffwll.local> <20180417205744.GA15930@downor-Z87X-UD5H> <41487acb-a67a-8933-d0c3-702c19b0938e@gmail.com> <20180418073508.ptvntwedczpvl7bx@MacBook-Pro-de-Roger.local> <20180418101058.hyqk3gr3b2ibxswu@MacBook-Pro-de-Roger.local> <20180420071914.GG31310@phenom.ffwll.local> <76cdc65a-7bb1-9377-7bc5-6164e32f7b5d@gmail.com> <20180423115242.ywdwqblj2aseu3fr@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; Format="flowed" Content-Transfer-Encoding: base64 Return-path: Received: from mail-lf0-x241.google.com (mail-lf0-x241.google.com [IPv6:2a00:1450:4010:c07::241]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8FADD89854 for ; Mon, 23 Apr 2018 12:10:39 +0000 (UTC) Received: by mail-lf0-x241.google.com with SMTP id v207-v6so14538543lfa.10 for ; Mon, 23 Apr 2018 05:10:39 -0700 (PDT) In-Reply-To: <20180423115242.ywdwqblj2aseu3fr@citrix.com> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Wei Liu Cc: jgross@suse.com, Artem Mygaiev , Dongwon Kim , konrad.wilk@oracle.com, airlied@linux.ie, "Oleksandr_Andrushchenko@epam.com" , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, "Potrola, MateuszX" , daniel.vetter@intel.com, xen-devel@lists.xenproject.org, boris.ostrovsky@oracle.com, =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= List-Id: dri-devel@lists.freedesktop.org T24gMDQvMjMvMjAxOCAwMjo1MiBQTSwgV2VpIExpdSB3cm90ZToKPiBPbiBGcmksIEFwciAyMCwg MjAxOCBhdCAwMjoyNToyMFBNICswMzAwLCBPbGVrc2FuZHIgQW5kcnVzaGNoZW5rbyB3cm90ZToK Pj4+PiAgICAgIHRoZSBnbnRkZXYuCj4+Pj4KPj4+PiBJIHRoaW5rIHRoaXMgaXMgZ2VuZXJpYyBl bm91Z2ggdGhhdCBpdCBjb3VsZCBiZSBpbXBsZW1lbnRlZCBieSBhCj4+Pj4gZGV2aWNlIG5vdCB0 aWVkIHRvIFhlbi4gQUZBSUNUIHRoZSBoeXBlcl9kbWEgZ3V5cyBhbHNvIHdhbnRlZAo+Pj4+IHNv bWV0aGluZyBzaW1pbGFyIHRvIHRoaXMuCj4+PiBZb3UgY2FuJ3QganVzdCB3cmFwIHJhbmRvbSB1 c2Vyc3BhY2UgbWVtb3J5IGludG8gYSBkbWEtYnVmLiBXZSd2ZSBqdXN0IGhhZAo+Pj4gdGhpcyBk aXNjdXNzaW9uIHdpdGgga3ZtL3FlbXUgZm9sa3MsIHdobyBwcm9wb3NlZCBqdXN0IHRoYXQsIGFu ZCBhZnRlciBhCj4+PiBiaXQgb2YgZGlzY3Vzc2lvbiB0aGV5J2xsIG5vdyB0cnkgdG8gaGF2ZSBh IGRyaXZlciB3aGljaCBqdXN0IHdyYXBzIGEKPj4+IG1lbWZkIGludG8gYSBkbWEtYnVmLgo+PiBT bywgd2UgaGF2ZSB0byBkZWNpZGUgZWl0aGVyIHdlIGludHJvZHVjZSBhIG5ldyBkcml2ZXIKPj4g KHNheSwgdW5kZXIgZHJpdmVycy94ZW4veGVuLWRtYS1idWYpIG9yIGV4dGVuZCB0aGUgZXhpc3Rp bmcKPj4gZ250ZGV2L2JhbGxvb24gdG8gc3VwcG9ydCBkbWEtYnVmIHVzZS1jYXNlcy4KPj4KPj4g Q2FuIGFueWJvZHkgZnJvbSBYZW4gY29tbXVuaXR5IGV4cHJlc3MgdGhlaXIgcHJlZmVyZW5jZSBo ZXJlPwo+Pgo+IE9sZWtzYW5kciB0YWxrZWQgdG8gbWUgb24gSVJDIGFib3V0IHRoaXMsIGhlIHNh aWQgYSBmZXcgSU9DVExzIG5lZWQgdG8KPiBiZSBhZGRlZCB0byBlaXRoZXIgZXhpc3RpbmcgZHJp dmVycyBvciBhIG5ldyBkcml2ZXIuCj4KPiBJIHdlbnQgdGhyb3VnaCB0aGlzIHRocmVhZCB0d2lj ZSBhbmQgc2tpbW1lZCB0aHJvdWdoIHRoZSByZWxldmFudAo+IGRvY3VtZW50cywgYnV0IEkgY291 bGRuJ3Qgc2VlIGFueSBvYnZpb3VzIHByb3MgYW5kIGNvbnMgZm9yIGVpdGhlcgo+IGFwcHJvYWNo LiBTbyBJIGRvbid0IHJlYWxseSBoYXZlIGFuIG9waW5pb24gb24gdGhpcy4KPgo+IEJ1dCwgYXNz dW1pbmcgaWYgaW1wbGVtZW50ZWQgaW4gZXhpc3RpbmcgZHJpdmVycywgdGhvc2UgSU9DVExzIG5l ZWQgdG8KPiBiZSBhZGRlZCB0byBkaWZmZXJlbnQgZHJpdmVycywgd2hpY2ggbWVhbnMgdXNlcnNw YWNlIHByb2dyYW0gbmVlZHMgdG8KPiB3cml0ZSBtb3JlIGNvZGUgYW5kIGdldCBtb3JlIGhhbmRs ZXMsIGl0IHdvdWxkIGJlIHNsaWdodGx5IGJldHRlciB0bwo+IGltcGxlbWVudCBhIG5ldyBkcml2 ZXIgZnJvbSB0aGF0IHBlcnNwZWN0aXZlLgpJZiBnbnRkZXYvYmFsbG9vbiBleHRlbnNpb24gaXMg c3RpbGwgY29uc2lkZXJlZDoKCkFsbCB0aGUgSU9DVExzIHdpbGwgYmUgaW4gZ250ZGV2IGRyaXZl ciAoaW4gY3VycmVudCB4ZW4temNvcHkgdGVybWlub2xvZ3kpOgogwqAtIERSTV9JQ09UTF9YRU5f WkNPUFlfRFVNQl9GUk9NX1JFRlMKIMKgLSBEUk1fSU9DVExfWEVOX1pDT1BZX0RVTUJfVE9fUkVG UwogwqAtIERSTV9JT0NUTF9YRU5fWkNPUFlfRFVNQl9XQUlUX0ZSRUUKCkJhbGxvb24gZHJpdmVy IGV4dGVuc2lvbiwgd2hpY2ggaXMgbmVlZGVkIGZvciBjb250aWd1b3VzL0RNQQpidWZmZXJzLCB3 aWxsIGJlIHRvIHByb3ZpZGUgbmV3ICprZXJuZWwgQVBJKiwgbm8gVUFQSSBpcyBuZWVkZWQuCgo+ IFdlaS4KVGhhbmsgeW91LApPbGVrc2FuZHIKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX18KZHJpLWRldmVsIG1haWxpbmcgbGlzdApkcmktZGV2ZWxAbGlzdHMu ZnJlZWRlc2t0b3Aub3JnCmh0dHBzOi8vbGlzdHMuZnJlZWRlc2t0b3Aub3JnL21haWxtYW4vbGlz dGluZm8vZHJpLWRldmVsCg==