Re: [PATCH v6 0/4] Add a vhost RPMsg API
Hi Guennadi, On 9/18/20 11:47 AM, Guennadi Liakhovetski wrote: > Hi Arnaud, > > On Fri, Sep 18, 2020 at 09:47:45AM +0200, Arnaud POULIQUEN wrote: >> Hi Guennadi, >> >> On 9/18/20 7:44 AM, Guennadi Liakhovetski wrote: >>> Hi Arnaud, >>> >>> On Thu, Sep 17, 2020 at 05:21:02PM +0200, Arnaud POULIQUEN wrote: >>>> Hi Guennadi, >>>> >>>>> -Original Message- >>>>> From: Guennadi Liakhovetski >>>>> Sent: jeudi 17 septembre 2020 07:47 >>>>> To: Arnaud POULIQUEN >>>>> Cc: k...@vger.kernel.org; linux-remotep...@vger.kernel.org; >>>>> virtualization@lists.linux-foundation.org; sound-open-firmware@alsa- >>>>> project.org; Pierre-Louis Bossart ; >>>>> Liam >>>>> Girdwood ; Michael S. Tsirkin >>>>> ; Jason Wang ; Ohad Ben-Cohen >>>>> ; Bjorn Andersson ; Mathieu >>>>> Poirier ; Vincent Whitchurch >>>>> >>>>> Subject: Re: [PATCH v6 0/4] Add a vhost RPMsg API >>>>> >>>>> Hi Arnaud, >>>>> >>>>> On Tue, Sep 15, 2020 at 02:13:23PM +0200, Arnaud POULIQUEN wrote: >>>>>> Hi Guennadi, >>>>>> >>>>>> On 9/1/20 5:11 PM, Guennadi Liakhovetski wrote: >>>>>>> Hi, >>>>>>> >>>>>>> Next update: >>>>>>> >>>>>>> v6: >>>>>>> - rename include/linux/virtio_rpmsg.h -> >>>>>>> include/linux/rpmsg/virtio.h >>>>>>> >>>>>>> v5: >>>>>>> - don't hard-code message layout >>>>>>> >>>>>>> v4: >>>>>>> - add endianness conversions to comply with the VirtIO standard >>>>>>> >>>>>>> v3: >>>>>>> - address several checkpatch warnings >>>>>>> - address comments from Mathieu Poirier >>>>>>> >>>>>>> v2: >>>>>>> - update patch #5 with a correct vhost_dev_init() prototype >>>>>>> - drop patch #6 - it depends on a different patch, that is currently >>>>>>> an RFC >>>>>>> - address comments from Pierre-Louis Bossart: >>>>>>> * remove "default n" from Kconfig >>>>>>> >>>>>>> Linux supports RPMsg over VirtIO for "remote processor" / AMP use >>>>>>> cases. It can however also be used for virtualisation scenarios, >>>>>>> e.g. when using KVM to run Linux on both the host and the guests. >>>>>>> This patch set adds a wrapper API to facilitate writing vhost >>>>>>> drivers for such RPMsg-based solutions. The first use case is an >>>>>>> audio DSP virtualisation project, currently under development, ready >>>>>>> for review and submission, available at >>>>>>> https://github.com/thesofproject/linux/pull/1501/commits >>>>>> >>>>>> Mathieu pointed me your series. On my side i proposed the rpmsg_ns_msg >>>>>> service[1] that does not match with your implementation. >>>>>> As i come late, i hope that i did not miss something in the history... >>>>>> Don't hesitate to point me the discussions, if it is the case. >>>>> >>>>> Well, as you see, this is a v6 only of this patch set, and apart from it >>>>> there have >>>>> been several side discussions and patch sets. >>>>> >>>>>> Regarding your patchset, it is quite confusing for me. It seems that >>>>>> you implement your own protocol on top of vhost forked from the RPMsg >>>>> one. >>>>>> But look to me that it is not the RPMsg protocol. >>>>> >>>>> I'm implementing a counterpart to the rpmsg protocol over VirtIO as >>>>> initially >>>>> implemented by drivers/rpmsg/virtio_rpmsg_bus.c for the "main CPU" (in >>>>> case >>>>> of remoteproc over VirtIO) or the guest side in case of Linux >>>>> virtualisation. >>>>> Since my implementation can talk to that driver, I don't think, that I'm >>>>> inventing >>>>> a new protocol. I'm adding support for the same protocol for the opposite >>>>> side >>&
Re: [PATCH v6 0/4] Add a vhost RPMsg API
On Fri, Sep 18, 2020 at 12:39:07PM +0200, Vincent Whitchurch wrote: > On Fri, Sep 18, 2020 at 11:47:20AM +0200, Guennadi Liakhovetski wrote: > > On Fri, Sep 18, 2020 at 09:47:45AM +0200, Arnaud POULIQUEN wrote: > > > IMO, as this API is defined in the Linux documentation [5] we should > > > respect it, to ensure > > > one generic implementation. The RPMsg sample client[4] uses this user > > > API, so seems to me > > > a good candidate to verify this. > > > > > > That's said, shall we multiple the RPMsg implementations in Linux with > > > several APIs, > > > With the risk to make the RPMsg clients devices dependent on these > > > implementations? > > > That could lead to complex code or duplications... > > > > So, no, in my understanding there aren't two competing alternative APIs, > > you'd never have > > to choose between them. If you're writing a driver for Linux to communicate > > with remote > > processors or to run on VMs, you use the existing API. If you're writing a > > driver for > > Linux to communicate with those VMs, you use the vhost API and whatever > > help is available > > for RPMsg processing. > > > > However, I can in principle imagine a single driver, written to work on > > both sides. > > Something like the rpmsg_char.c or maybe some networking driver. Is that > > what you're > > referring to? I can see that as a fun exercise, but are there any real uses > > for that? > > I hinted at a real use case for this in the previous mail thread[0]. > I'm exploring using rpmsg-char to allow communication between two chips, > both running Linux. rpmsg-char can be used pretty much as-is for both > sides of the userspace-to-userspace communication and (the userspace > side of the) userspace-to-kernel communication between the two chips. > > > You could do the same with VirtIO, however, it has been decided to go with > > two > > distinct APIs: virtio for guests and vhost for the host, noone bothered to > > create a > > single API for both and nobody seems to miss one. Why would we want one > > with RPMsg? > > I think I answered this question in the previous mail thread as well[1]: > | virtio has distinct driver and device roles so the completely different > | APIs on each side are understandable. But I don't see that distinction > | in the rpmsg API which is why it seems like a good idea to me to make it > | work from both sides of the link and allow the reuse of drivers like > | rpmsg-char, instead of imposing virtio's distinction on rpmsg. I think RPMsg is lacking real established documentation... Quating from [2]: In the current protocol, at startup, the master sends notification to remote to let it know that it can receive name service announcement. Isn't that a sufficient asymnetry? Thanks Guennadi [2] https://github.com/OpenAMP/open-amp/wiki/RPMsg-Messaging-Protocol > > [0] https://www.spinics.net/lists/linux-virtualization/msg43799.html > [1] https://www.spinics.net/lists/linux-virtualization/msg43802.html ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v6 0/4] Add a vhost RPMsg API
On Fri, Sep 18, 2020 at 11:47:20AM +0200, Guennadi Liakhovetski wrote: > On Fri, Sep 18, 2020 at 09:47:45AM +0200, Arnaud POULIQUEN wrote: > > IMO, as this API is defined in the Linux documentation [5] we should > > respect it, to ensure > > one generic implementation. The RPMsg sample client[4] uses this user API, > > so seems to me > > a good candidate to verify this. > > > > That's said, shall we multiple the RPMsg implementations in Linux with > > several APIs, > > With the risk to make the RPMsg clients devices dependent on these > > implementations? > > That could lead to complex code or duplications... > > So, no, in my understanding there aren't two competing alternative APIs, > you'd never have > to choose between them. If you're writing a driver for Linux to communicate > with remote > processors or to run on VMs, you use the existing API. If you're writing a > driver for > Linux to communicate with those VMs, you use the vhost API and whatever help > is available > for RPMsg processing. > > However, I can in principle imagine a single driver, written to work on both > sides. > Something like the rpmsg_char.c or maybe some networking driver. Is that what > you're > referring to? I can see that as a fun exercise, but are there any real uses > for that? I hinted at a real use case for this in the previous mail thread[0]. I'm exploring using rpmsg-char to allow communication between two chips, both running Linux. rpmsg-char can be used pretty much as-is for both sides of the userspace-to-userspace communication and (the userspace side of the) userspace-to-kernel communication between the two chips. > You could do the same with VirtIO, however, it has been decided to go with > two > distinct APIs: virtio for guests and vhost for the host, noone bothered to > create a > single API for both and nobody seems to miss one. Why would we want one with > RPMsg? I think I answered this question in the previous mail thread as well[1]: | virtio has distinct driver and device roles so the completely different | APIs on each side are understandable. But I don't see that distinction | in the rpmsg API which is why it seems like a good idea to me to make it | work from both sides of the link and allow the reuse of drivers like | rpmsg-char, instead of imposing virtio's distinction on rpmsg. [0] https://www.spinics.net/lists/linux-virtualization/msg43799.html [1] https://www.spinics.net/lists/linux-virtualization/msg43802.html ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v6 0/4] Add a vhost RPMsg API
Hi Arnaud, On Fri, Sep 18, 2020 at 09:47:45AM +0200, Arnaud POULIQUEN wrote: > Hi Guennadi, > > On 9/18/20 7:44 AM, Guennadi Liakhovetski wrote: > > Hi Arnaud, > > > > On Thu, Sep 17, 2020 at 05:21:02PM +0200, Arnaud POULIQUEN wrote: > >> Hi Guennadi, > >> > >>> -Original Message- > >>> From: Guennadi Liakhovetski > >>> Sent: jeudi 17 septembre 2020 07:47 > >>> To: Arnaud POULIQUEN > >>> Cc: k...@vger.kernel.org; linux-remotep...@vger.kernel.org; > >>> virtualization@lists.linux-foundation.org; sound-open-firmware@alsa- > >>> project.org; Pierre-Louis Bossart ; > >>> Liam > >>> Girdwood ; Michael S. Tsirkin > >>> ; Jason Wang ; Ohad Ben-Cohen > >>> ; Bjorn Andersson ; Mathieu > >>> Poirier ; Vincent Whitchurch > >>> > >>> Subject: Re: [PATCH v6 0/4] Add a vhost RPMsg API > >>> > >>> Hi Arnaud, > >>> > >>> On Tue, Sep 15, 2020 at 02:13:23PM +0200, Arnaud POULIQUEN wrote: > >>>> Hi Guennadi, > >>>> > >>>> On 9/1/20 5:11 PM, Guennadi Liakhovetski wrote: > >>>>> Hi, > >>>>> > >>>>> Next update: > >>>>> > >>>>> v6: > >>>>> - rename include/linux/virtio_rpmsg.h -> > >>>>> include/linux/rpmsg/virtio.h > >>>>> > >>>>> v5: > >>>>> - don't hard-code message layout > >>>>> > >>>>> v4: > >>>>> - add endianness conversions to comply with the VirtIO standard > >>>>> > >>>>> v3: > >>>>> - address several checkpatch warnings > >>>>> - address comments from Mathieu Poirier > >>>>> > >>>>> v2: > >>>>> - update patch #5 with a correct vhost_dev_init() prototype > >>>>> - drop patch #6 - it depends on a different patch, that is currently > >>>>> an RFC > >>>>> - address comments from Pierre-Louis Bossart: > >>>>> * remove "default n" from Kconfig > >>>>> > >>>>> Linux supports RPMsg over VirtIO for "remote processor" / AMP use > >>>>> cases. It can however also be used for virtualisation scenarios, > >>>>> e.g. when using KVM to run Linux on both the host and the guests. > >>>>> This patch set adds a wrapper API to facilitate writing vhost > >>>>> drivers for such RPMsg-based solutions. The first use case is an > >>>>> audio DSP virtualisation project, currently under development, ready > >>>>> for review and submission, available at > >>>>> https://github.com/thesofproject/linux/pull/1501/commits > >>>> > >>>> Mathieu pointed me your series. On my side i proposed the rpmsg_ns_msg > >>>> service[1] that does not match with your implementation. > >>>> As i come late, i hope that i did not miss something in the history... > >>>> Don't hesitate to point me the discussions, if it is the case. > >>> > >>> Well, as you see, this is a v6 only of this patch set, and apart from it > >>> there have > >>> been several side discussions and patch sets. > >>> > >>>> Regarding your patchset, it is quite confusing for me. It seems that > >>>> you implement your own protocol on top of vhost forked from the RPMsg > >>> one. > >>>> But look to me that it is not the RPMsg protocol. > >>> > >>> I'm implementing a counterpart to the rpmsg protocol over VirtIO as > >>> initially > >>> implemented by drivers/rpmsg/virtio_rpmsg_bus.c for the "main CPU" (in > >>> case > >>> of remoteproc over VirtIO) or the guest side in case of Linux > >>> virtualisation. > >>> Since my implementation can talk to that driver, I don't think, that I'm > >>> inventing > >>> a new protocol. I'm adding support for the same protocol for the opposite > >>> side > >>> of the VirtIO divide. > >> > >> The main point I would like to highlight here is related to the use of the > >> name "RPMsg" > >> more than how you implement your IPC protocol. > >> If It is a counterpart, it probably does not respect interface for RPMsg > >> clients. > &g
Re: [PATCH v6 0/4] Add a vhost RPMsg API
Hi Guennadi, On 9/18/20 7:44 AM, Guennadi Liakhovetski wrote: > Hi Arnaud, > > On Thu, Sep 17, 2020 at 05:21:02PM +0200, Arnaud POULIQUEN wrote: >> Hi Guennadi, >> >>> -Original Message- >>> From: Guennadi Liakhovetski >>> Sent: jeudi 17 septembre 2020 07:47 >>> To: Arnaud POULIQUEN >>> Cc: k...@vger.kernel.org; linux-remotep...@vger.kernel.org; >>> virtualization@lists.linux-foundation.org; sound-open-firmware@alsa- >>> project.org; Pierre-Louis Bossart ; >>> Liam >>> Girdwood ; Michael S. Tsirkin >>> ; Jason Wang ; Ohad Ben-Cohen >>> ; Bjorn Andersson ; Mathieu >>> Poirier ; Vincent Whitchurch >>> >>> Subject: Re: [PATCH v6 0/4] Add a vhost RPMsg API >>> >>> Hi Arnaud, >>> >>> On Tue, Sep 15, 2020 at 02:13:23PM +0200, Arnaud POULIQUEN wrote: >>>> Hi Guennadi, >>>> >>>> On 9/1/20 5:11 PM, Guennadi Liakhovetski wrote: >>>>> Hi, >>>>> >>>>> Next update: >>>>> >>>>> v6: >>>>> - rename include/linux/virtio_rpmsg.h -> >>>>> include/linux/rpmsg/virtio.h >>>>> >>>>> v5: >>>>> - don't hard-code message layout >>>>> >>>>> v4: >>>>> - add endianness conversions to comply with the VirtIO standard >>>>> >>>>> v3: >>>>> - address several checkpatch warnings >>>>> - address comments from Mathieu Poirier >>>>> >>>>> v2: >>>>> - update patch #5 with a correct vhost_dev_init() prototype >>>>> - drop patch #6 - it depends on a different patch, that is currently >>>>> an RFC >>>>> - address comments from Pierre-Louis Bossart: >>>>> * remove "default n" from Kconfig >>>>> >>>>> Linux supports RPMsg over VirtIO for "remote processor" / AMP use >>>>> cases. It can however also be used for virtualisation scenarios, >>>>> e.g. when using KVM to run Linux on both the host and the guests. >>>>> This patch set adds a wrapper API to facilitate writing vhost >>>>> drivers for such RPMsg-based solutions. The first use case is an >>>>> audio DSP virtualisation project, currently under development, ready >>>>> for review and submission, available at >>>>> https://github.com/thesofproject/linux/pull/1501/commits >>>> >>>> Mathieu pointed me your series. On my side i proposed the rpmsg_ns_msg >>>> service[1] that does not match with your implementation. >>>> As i come late, i hope that i did not miss something in the history... >>>> Don't hesitate to point me the discussions, if it is the case. >>> >>> Well, as you see, this is a v6 only of this patch set, and apart from it >>> there have >>> been several side discussions and patch sets. >>> >>>> Regarding your patchset, it is quite confusing for me. It seems that >>>> you implement your own protocol on top of vhost forked from the RPMsg >>> one. >>>> But look to me that it is not the RPMsg protocol. >>> >>> I'm implementing a counterpart to the rpmsg protocol over VirtIO as >>> initially >>> implemented by drivers/rpmsg/virtio_rpmsg_bus.c for the "main CPU" (in case >>> of remoteproc over VirtIO) or the guest side in case of Linux >>> virtualisation. >>> Since my implementation can talk to that driver, I don't think, that I'm >>> inventing >>> a new protocol. I'm adding support for the same protocol for the opposite >>> side >>> of the VirtIO divide. >> >> The main point I would like to highlight here is related to the use of the >> name "RPMsg" >> more than how you implement your IPC protocol. >> If It is a counterpart, it probably does not respect interface for RPMsg >> clients. >> A good way to answer this, might be to respond to this question: >> Is the rpmsg sample client[4] can be used on top of your vhost RPMsg >> implementation? >> If the response is no, describe it as a RPMsg implementation could lead to >> confusion... > > Sorry, I don't quite understand your logic. RPMsg is a communication > protocol, not an > API. An RPMsg implementation has to be able to communicate with other > compliant RPMsg > implementations, it doesn't have to provide any specific API. Am I missin
Re: [PATCH v6 0/4] Add a vhost RPMsg API
Hi Arnaud, On Thu, Sep 17, 2020 at 05:21:02PM +0200, Arnaud POULIQUEN wrote: > Hi Guennadi, > > > -Original Message- > > From: Guennadi Liakhovetski > > Sent: jeudi 17 septembre 2020 07:47 > > To: Arnaud POULIQUEN > > Cc: k...@vger.kernel.org; linux-remotep...@vger.kernel.org; > > virtualization@lists.linux-foundation.org; sound-open-firmware@alsa- > > project.org; Pierre-Louis Bossart ; > > Liam > > Girdwood ; Michael S. Tsirkin > > ; Jason Wang ; Ohad Ben-Cohen > > ; Bjorn Andersson ; Mathieu > > Poirier ; Vincent Whitchurch > > > > Subject: Re: [PATCH v6 0/4] Add a vhost RPMsg API > > > > Hi Arnaud, > > > > On Tue, Sep 15, 2020 at 02:13:23PM +0200, Arnaud POULIQUEN wrote: > > > Hi Guennadi, > > > > > > On 9/1/20 5:11 PM, Guennadi Liakhovetski wrote: > > > > Hi, > > > > > > > > Next update: > > > > > > > > v6: > > > > - rename include/linux/virtio_rpmsg.h -> > > > > include/linux/rpmsg/virtio.h > > > > > > > > v5: > > > > - don't hard-code message layout > > > > > > > > v4: > > > > - add endianness conversions to comply with the VirtIO standard > > > > > > > > v3: > > > > - address several checkpatch warnings > > > > - address comments from Mathieu Poirier > > > > > > > > v2: > > > > - update patch #5 with a correct vhost_dev_init() prototype > > > > - drop patch #6 - it depends on a different patch, that is currently > > > > an RFC > > > > - address comments from Pierre-Louis Bossart: > > > > * remove "default n" from Kconfig > > > > > > > > Linux supports RPMsg over VirtIO for "remote processor" / AMP use > > > > cases. It can however also be used for virtualisation scenarios, > > > > e.g. when using KVM to run Linux on both the host and the guests. > > > > This patch set adds a wrapper API to facilitate writing vhost > > > > drivers for such RPMsg-based solutions. The first use case is an > > > > audio DSP virtualisation project, currently under development, ready > > > > for review and submission, available at > > > > https://github.com/thesofproject/linux/pull/1501/commits > > > > > > Mathieu pointed me your series. On my side i proposed the rpmsg_ns_msg > > > service[1] that does not match with your implementation. > > > As i come late, i hope that i did not miss something in the history... > > > Don't hesitate to point me the discussions, if it is the case. > > > > Well, as you see, this is a v6 only of this patch set, and apart from it > > there have > > been several side discussions and patch sets. > > > > > Regarding your patchset, it is quite confusing for me. It seems that > > > you implement your own protocol on top of vhost forked from the RPMsg > > one. > > > But look to me that it is not the RPMsg protocol. > > > > I'm implementing a counterpart to the rpmsg protocol over VirtIO as > > initially > > implemented by drivers/rpmsg/virtio_rpmsg_bus.c for the "main CPU" (in case > > of remoteproc over VirtIO) or the guest side in case of Linux > > virtualisation. > > Since my implementation can talk to that driver, I don't think, that I'm > > inventing > > a new protocol. I'm adding support for the same protocol for the opposite > > side > > of the VirtIO divide. > > The main point I would like to highlight here is related to the use of the > name "RPMsg" > more than how you implement your IPC protocol. > If It is a counterpart, it probably does not respect interface for RPMsg > clients. > A good way to answer this, might be to respond to this question: > Is the rpmsg sample client[4] can be used on top of your vhost RPMsg > implementation? > If the response is no, describe it as a RPMsg implementation could lead to > confusion... Sorry, I don't quite understand your logic. RPMsg is a communication protocol, not an API. An RPMsg implementation has to be able to communicate with other compliant RPMsg implementations, it doesn't have to provide any specific API. Am I missing anything? Thanks Guennadi > [4] > https://elixir.bootlin.com/linux/v5.9-rc5/source/samples/rpmsg/rpmsg_client_sample.c > > Regards, > Arnaud > > > > > > So i would be agree with Vincent[2] which proposed to switch on a > > > RPMsg API and creating a vhost
RE: [PATCH v6 0/4] Add a vhost RPMsg API
Hi Guennadi, > -Original Message- > From: Guennadi Liakhovetski > Sent: jeudi 17 septembre 2020 07:47 > To: Arnaud POULIQUEN > Cc: k...@vger.kernel.org; linux-remotep...@vger.kernel.org; > virtualization@lists.linux-foundation.org; sound-open-firmware@alsa- > project.org; Pierre-Louis Bossart ; Liam > Girdwood ; Michael S. Tsirkin > ; Jason Wang ; Ohad Ben-Cohen > ; Bjorn Andersson ; Mathieu > Poirier ; Vincent Whitchurch > > Subject: Re: [PATCH v6 0/4] Add a vhost RPMsg API > > Hi Arnaud, > > On Tue, Sep 15, 2020 at 02:13:23PM +0200, Arnaud POULIQUEN wrote: > > Hi Guennadi, > > > > On 9/1/20 5:11 PM, Guennadi Liakhovetski wrote: > > > Hi, > > > > > > Next update: > > > > > > v6: > > > - rename include/linux/virtio_rpmsg.h -> > > > include/linux/rpmsg/virtio.h > > > > > > v5: > > > - don't hard-code message layout > > > > > > v4: > > > - add endianness conversions to comply with the VirtIO standard > > > > > > v3: > > > - address several checkpatch warnings > > > - address comments from Mathieu Poirier > > > > > > v2: > > > - update patch #5 with a correct vhost_dev_init() prototype > > > - drop patch #6 - it depends on a different patch, that is currently > > > an RFC > > > - address comments from Pierre-Louis Bossart: > > > * remove "default n" from Kconfig > > > > > > Linux supports RPMsg over VirtIO for "remote processor" / AMP use > > > cases. It can however also be used for virtualisation scenarios, > > > e.g. when using KVM to run Linux on both the host and the guests. > > > This patch set adds a wrapper API to facilitate writing vhost > > > drivers for such RPMsg-based solutions. The first use case is an > > > audio DSP virtualisation project, currently under development, ready > > > for review and submission, available at > > > https://github.com/thesofproject/linux/pull/1501/commits > > > > Mathieu pointed me your series. On my side i proposed the rpmsg_ns_msg > > service[1] that does not match with your implementation. > > As i come late, i hope that i did not miss something in the history... > > Don't hesitate to point me the discussions, if it is the case. > > Well, as you see, this is a v6 only of this patch set, and apart from it > there have > been several side discussions and patch sets. > > > Regarding your patchset, it is quite confusing for me. It seems that > > you implement your own protocol on top of vhost forked from the RPMsg > one. > > But look to me that it is not the RPMsg protocol. > > I'm implementing a counterpart to the rpmsg protocol over VirtIO as initially > implemented by drivers/rpmsg/virtio_rpmsg_bus.c for the "main CPU" (in case > of remoteproc over VirtIO) or the guest side in case of Linux virtualisation. > Since my implementation can talk to that driver, I don't think, that I'm > inventing > a new protocol. I'm adding support for the same protocol for the opposite side > of the VirtIO divide. The main point I would like to highlight here is related to the use of the name "RPMsg" more than how you implement your IPC protocol. If It is a counterpart, it probably does not respect interface for RPMsg clients. A good way to answer this, might be to respond to this question: Is the rpmsg sample client[4] can be used on top of your vhost RPMsg implementation? If the response is no, describe it as a RPMsg implementation could lead to confusion... [4] https://elixir.bootlin.com/linux/v5.9-rc5/source/samples/rpmsg/rpmsg_client_sample.c Regards, Arnaud > > > So i would be agree with Vincent[2] which proposed to switch on a > > RPMsg API and creating a vhost rpmsg device. This is also proposed in > > the "Enhance VHOST to enable SoC-to-SoC communication" RFC[3]. > > Do you think that this alternative could match with your need? > > As I replied to Vincent, I understand his proposal and the approach taken in > the > series [3], but I'm not sure I agree, that adding yet another virtual device / > driver layer on the vhost side is a good idea. As far as I understand adding > new > completely virtual devices isn't considered to be a good practice in the > kernel. > Currently vhost is just a passive "library" > and my vhost-rpmsg support keeps it that way. Not sure I'm in favour of > converting vhost to a virtual device infrastructure. > > Thanks for pointing me out at [3], I should have a better look at it. > > Thanks > Guennadi > > > [1]
Re: [PATCH v6 0/4] Add a vhost RPMsg API
Hi Vincent, On Thu, Sep 17, 2020 at 10:36:44AM +0200, Vincent Whitchurch wrote: > On Thu, Sep 17, 2020 at 07:47:06AM +0200, Guennadi Liakhovetski wrote: > > On Tue, Sep 15, 2020 at 02:13:23PM +0200, Arnaud POULIQUEN wrote: > > > So i would be agree with Vincent[2] which proposed to switch on a RPMsg > > > API > > > and creating a vhost rpmsg device. This is also proposed in the > > > "Enhance VHOST to enable SoC-to-SoC communication" RFC[3]. > > > Do you think that this alternative could match with your need? > > > > As I replied to Vincent, I understand his proposal and the approach taken > > in the series [3], but I'm not sure I agree, that adding yet another > > virtual device / driver layer on the vhost side is a good idea. As far as > > I understand adding new completely virtual devices isn't considered to be > > a good practice in the kernel. Currently vhost is just a passive "library" > > and my vhost-rpmsg support keeps it that way. Not sure I'm in favour of > > converting vhost to a virtual device infrastructure. > > I know it wasn't what you meant, but I noticed that the above paragraph > could be read as if my suggestion was to convert vhost to a virtual > device infrastructure, so I just want to clarify that that those are not > related. The only similarity between what I suggested in the thread in > [2] and Kishon's RFC in [3] is that both involve creating a generic > vhost-rpmsg driver which would allow the RPMsg API to be used for both > sides of the link, instead of introducing a new API just for the server > side. That can be done without rewriting drivers/vhost/. Thanks for the clarification. Another flexibility, that I'm trying to preserve with my approach is keeping direct access to iovec style data buffers for cases where that's the structure, that's already used by the respective driver on the host side. Since we already do packing and unpacking on the guest / client side, we don't need the same on the host / server side again. Thanks Guennadi > > > [1]. > > > https://patchwork.kernel.org/project/linux-remoteproc/list/?series=338335 > > > [2]. https://www.spinics.net/lists/linux-virtualization/msg44195.html > > > [3]. https://www.spinics.net/lists/linux-remoteproc/msg06634.html ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v6 0/4] Add a vhost RPMsg API
On Thu, Sep 17, 2020 at 07:47:06AM +0200, Guennadi Liakhovetski wrote: > On Tue, Sep 15, 2020 at 02:13:23PM +0200, Arnaud POULIQUEN wrote: > > So i would be agree with Vincent[2] which proposed to switch on a RPMsg API > > and creating a vhost rpmsg device. This is also proposed in the > > "Enhance VHOST to enable SoC-to-SoC communication" RFC[3]. > > Do you think that this alternative could match with your need? > > As I replied to Vincent, I understand his proposal and the approach taken > in the series [3], but I'm not sure I agree, that adding yet another > virtual device / driver layer on the vhost side is a good idea. As far as > I understand adding new completely virtual devices isn't considered to be > a good practice in the kernel. Currently vhost is just a passive "library" > and my vhost-rpmsg support keeps it that way. Not sure I'm in favour of > converting vhost to a virtual device infrastructure. I know it wasn't what you meant, but I noticed that the above paragraph could be read as if my suggestion was to convert vhost to a virtual device infrastructure, so I just want to clarify that that those are not related. The only similarity between what I suggested in the thread in [2] and Kishon's RFC in [3] is that both involve creating a generic vhost-rpmsg driver which would allow the RPMsg API to be used for both sides of the link, instead of introducing a new API just for the server side. That can be done without rewriting drivers/vhost/. > > [1]. > > https://patchwork.kernel.org/project/linux-remoteproc/list/?series=338335 > > [2]. https://www.spinics.net/lists/linux-virtualization/msg44195.html > > [3]. https://www.spinics.net/lists/linux-remoteproc/msg06634.html ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v6 0/4] Add a vhost RPMsg API
Hi Arnaud, On Tue, Sep 15, 2020 at 02:13:23PM +0200, Arnaud POULIQUEN wrote: > Hi Guennadi, > > On 9/1/20 5:11 PM, Guennadi Liakhovetski wrote: > > Hi, > > > > Next update: > > > > v6: > > - rename include/linux/virtio_rpmsg.h -> include/linux/rpmsg/virtio.h > > > > v5: > > - don't hard-code message layout > > > > v4: > > - add endianness conversions to comply with the VirtIO standard > > > > v3: > > - address several checkpatch warnings > > - address comments from Mathieu Poirier > > > > v2: > > - update patch #5 with a correct vhost_dev_init() prototype > > - drop patch #6 - it depends on a different patch, that is currently > > an RFC > > - address comments from Pierre-Louis Bossart: > > * remove "default n" from Kconfig > > > > Linux supports RPMsg over VirtIO for "remote processor" / AMP use > > cases. It can however also be used for virtualisation scenarios, > > e.g. when using KVM to run Linux on both the host and the guests. > > This patch set adds a wrapper API to facilitate writing vhost > > drivers for such RPMsg-based solutions. The first use case is an > > audio DSP virtualisation project, currently under development, ready > > for review and submission, available at > > https://github.com/thesofproject/linux/pull/1501/commits > > Mathieu pointed me your series. On my side i proposed the rpmsg_ns_msg > service[1] that does not match with your implementation. > As i come late, i hope that i did not miss something in the history... > Don't hesitate to point me the discussions, if it is the case. Well, as you see, this is a v6 only of this patch set, and apart from it there have been several side discussions and patch sets. > Regarding your patchset, it is quite confusing for me. It seems that you > implement your own protocol on top of vhost forked from the RPMsg one. > But look to me that it is not the RPMsg protocol. I'm implementing a counterpart to the rpmsg protocol over VirtIO as initially implemented by drivers/rpmsg/virtio_rpmsg_bus.c for the "main CPU" (in case of remoteproc over VirtIO) or the guest side in case of Linux virtualisation. Since my implementation can talk to that driver, I don't think, that I'm inventing a new protocol. I'm adding support for the same protocol for the opposite side of the VirtIO divide. > So i would be agree with Vincent[2] which proposed to switch on a RPMsg API > and creating a vhost rpmsg device. This is also proposed in the > "Enhance VHOST to enable SoC-to-SoC communication" RFC[3]. > Do you think that this alternative could match with your need? As I replied to Vincent, I understand his proposal and the approach taken in the series [3], but I'm not sure I agree, that adding yet another virtual device / driver layer on the vhost side is a good idea. As far as I understand adding new completely virtual devices isn't considered to be a good practice in the kernel. Currently vhost is just a passive "library" and my vhost-rpmsg support keeps it that way. Not sure I'm in favour of converting vhost to a virtual device infrastructure. Thanks for pointing me out at [3], I should have a better look at it. Thanks Guennadi > [1]. > https://patchwork.kernel.org/project/linux-remoteproc/list/?series=338335 > [2]. https://www.spinics.net/lists/linux-virtualization/msg44195.html > [3]. https://www.spinics.net/lists/linux-remoteproc/msg06634.html > > Thanks, > Arnaud > > > > > Thanks > > Guennadi > > > > Guennadi Liakhovetski (4): > > vhost: convert VHOST_VSOCK_SET_RUNNING to a generic ioctl > > rpmsg: move common structures and defines to headers > > rpmsg: update documentation > > vhost: add an RPMsg API > > > > Documentation/rpmsg.txt | 6 +- > > drivers/rpmsg/virtio_rpmsg_bus.c | 78 +-- > > drivers/vhost/Kconfig| 7 + > > drivers/vhost/Makefile | 3 + > > drivers/vhost/rpmsg.c| 373 +++ > > drivers/vhost/vhost_rpmsg.h | 74 ++ > > include/linux/rpmsg/virtio.h | 83 +++ > > include/uapi/linux/rpmsg.h | 3 + > > include/uapi/linux/vhost.h | 4 +- > > 9 files changed, 551 insertions(+), 80 deletions(-) > > create mode 100644 drivers/vhost/rpmsg.c > > create mode 100644 drivers/vhost/vhost_rpmsg.h > > create mode 100644 include/linux/rpmsg/virtio.h > > ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
