RE: [PATCH v3 15/15] vfio: Add struct device to vfio_device
> From: Jason Gunthorpe > Sent: Thursday, September 22, 2022 12:10 AM > > On Tue, Sep 20, 2022 at 10:55:40PM +, Tian, Kevin wrote: > > > From: Alex Williamson > > > Sent: Wednesday, September 21, 2022 4:27 AM > > > > > > On Fri, 9 Sep 2022 18:22:47 +0800 > > > Kevin Tian wrote: > > > > > > > From: Yi Liu > > > > > > > > and replace kref. With it a 'vfio-dev/vfioX' node is created under the > > > > sysfs path of the parent, indicating the device is bound to a vfio > > > > driver, e.g.: > > > > > > > > /sys/devices/pci\:6f/\:6f\:01.0/vfio-dev/vfio0 > > > > > > > > It is also a preparatory step toward adding cdev for supporting future > > > > device-oriented uAPI. > > > > > > > > Add Documentation/ABI/testing/sysfs-devices-vfio-dev. > > > > > > > > Also take this chance to rename chardev 'vfio' to 'vfio-group' in > > > > /proc/devices. > > > > > > What's the risk/reward here, is this just more aesthetically pleasing > > > symmetry vs 'vfio-dev'? The char major number to name association in > > > /proc/devices seems pretty obscure, but what due diligence have we > done > > > to make sure this doesn't break anyone? Thanks, > > > > I'm not sure whether the content of /proc/devices is considered as ABI. > > > > @Jason? > > Ah, I've forgotten why we got here - didn't we have a naming conflict > with the new stuff that is being introduced? No, we don't have. There is no new char dev introduced in this series. Later when device cdev is added a new device major will be allocated for 'vfio-dev'. It's at that time renaming existing 'vfio' to 'vfio-group' is probably clearer, which is what I understood from your earlier suggestion. > > ABI wise it is not a problem unless there is a real user, I'm not > aware of anything scanning /proc, that has been obsoleted by sysfs a > long time ago. > This is a good news.
Re: [PATCH v3 15/15] vfio: Add struct device to vfio_device
On Tue, Sep 20, 2022 at 10:55:40PM +, Tian, Kevin wrote: > > From: Alex Williamson > > Sent: Wednesday, September 21, 2022 4:27 AM > > > > On Fri, 9 Sep 2022 18:22:47 +0800 > > Kevin Tian wrote: > > > > > From: Yi Liu > > > > > > and replace kref. With it a 'vfio-dev/vfioX' node is created under the > > > sysfs path of the parent, indicating the device is bound to a vfio > > > driver, e.g.: > > > > > > /sys/devices/pci\:6f/\:6f\:01.0/vfio-dev/vfio0 > > > > > > It is also a preparatory step toward adding cdev for supporting future > > > device-oriented uAPI. > > > > > > Add Documentation/ABI/testing/sysfs-devices-vfio-dev. > > > > > > Also take this chance to rename chardev 'vfio' to 'vfio-group' in > > > /proc/devices. > > > > What's the risk/reward here, is this just more aesthetically pleasing > > symmetry vs 'vfio-dev'? The char major number to name association in > > /proc/devices seems pretty obscure, but what due diligence have we done > > to make sure this doesn't break anyone? Thanks, > > I'm not sure whether the content of /proc/devices is considered as ABI. > > @Jason? Ah, I've forgotten why we got here - didn't we have a naming conflict with the new stuff that is being introduced? ABI wise it is not a problem unless there is a real user, I'm not aware of anything scanning /proc, that has been obsoleted by sysfs a long time ago. Jason
RE: [PATCH v3 15/15] vfio: Add struct device to vfio_device
> From: Alex Williamson > Sent: Wednesday, September 21, 2022 4:27 AM > > On Fri, 9 Sep 2022 18:22:47 +0800 > Kevin Tian wrote: > > > From: Yi Liu > > > > and replace kref. With it a 'vfio-dev/vfioX' node is created under the > > sysfs path of the parent, indicating the device is bound to a vfio > > driver, e.g.: > > > > /sys/devices/pci\:6f/\:6f\:01.0/vfio-dev/vfio0 > > > > It is also a preparatory step toward adding cdev for supporting future > > device-oriented uAPI. > > > > Add Documentation/ABI/testing/sysfs-devices-vfio-dev. > > > > Also take this chance to rename chardev 'vfio' to 'vfio-group' in > > /proc/devices. > > What's the risk/reward here, is this just more aesthetically pleasing > symmetry vs 'vfio-dev'? The char major number to name association in > /proc/devices seems pretty obscure, but what due diligence have we done > to make sure this doesn't break anyone? Thanks, > I'm not sure whether the content of /proc/devices is considered as ABI. @Jason? But to be safe I can remove this change in next version. If it's the right thing to do such change after discussion then it can be done in a separate patch after.
Re: [PATCH v3 15/15] vfio: Add struct device to vfio_device
On Fri, 9 Sep 2022 18:22:47 +0800 Kevin Tian wrote: > From: Yi Liu > > and replace kref. With it a 'vfio-dev/vfioX' node is created under the > sysfs path of the parent, indicating the device is bound to a vfio > driver, e.g.: > > /sys/devices/pci\:6f/\:6f\:01.0/vfio-dev/vfio0 > > It is also a preparatory step toward adding cdev for supporting future > device-oriented uAPI. > > Add Documentation/ABI/testing/sysfs-devices-vfio-dev. > > Also take this chance to rename chardev 'vfio' to 'vfio-group' in > /proc/devices. What's the risk/reward here, is this just more aesthetically pleasing symmetry vs 'vfio-dev'? The char major number to name association in /proc/devices seems pretty obscure, but what due diligence have we done to make sure this doesn't break anyone? Thanks, Alex
