Hi Alex, On 08/27/2015 06:11 PM, Alex Williamson wrote: > On Thu, 2015-08-27 at 14:52 +0200, Eric Auger wrote: >> Hi Baptiste, Antonios, >> >> What are the plans wrt this series? I am currently integrating another >> QEMU VFIO platform devices where this series could be useful I think >> (Feb 2015). Do you intend to follow up and bring it upstream? >> >> Alex, do you see some show-stoppers in this series or do you advise to >> simply follow-up? > > I'm at a bit of a disadvantage not really knowing what types of > properties a user will be able to retrieve here. The interface itself > seems sort of like a game of Go Fish. Should the properties we're > looking for be generally available via sysfs? The ioctl proposed needs > some work to fit within the argsz/flags model that vfio typically uses. > It's unclear what argsz vs length represents and defining the flags > field as 'type' limits the future extensions of the ioctl. Thanks, The properties that I need can be found in /proc/device-tree too. They are of different types, with void cell value, with string cell values(single & multiple), with integer cell value(s), array ... The aim is to be able to assign a highly configurable platform device to a guest, read some property values on host and write the same values in guest dt node. Do you advise to read the fs directly instead of using such API? Thanks Eric > > Alex > >> On 12/19/2014 10:20 PM, Antonios Motakis wrote: >>> This RFC's intention is to show what an interface to access device >>> properties for the VFIO platform driver can look like. These properties >>> can be from the device tree node describing the device, or ACPI properties >>> in the future. >>> >>> If a device property corresponding to a platform device bound by VFIO PLATFORM >>> or VFIO AMBA is available, this patch series will allow the user to query >>> for this information. This can be useful for userspace drivers to automatically >>> query parameters related to the device. >>> >>> Specifically for QEMU, reading the "compatible" property of the device tree >>> node could be of use to find out what device is being assigned to the guest and >>> handle appropriately a wider range of devices in the future, and to generate an >>> appropriate device tree for the guest. >>> >>> Older versions of this series where specifically targeted at device tree >>> properties. This version has been reworked on top of Rafael J. Wysocki's >>> uniform device properties API for device tree and ACPI devices. This will allow >>> us to use the API in the future with devices described via ACPI. >>> >>> This also means a kernel including the uniform device properties API is needed >>> to apply these patches, in additon to the VFIO patches, e.g. branch pm+acpi-3.19-rc1 >>> from https://git.kernel.org/cgit/linux/kernel/git/rafael/linux-pm.git/ >>> >>> The API to get the list of available properties and the device tree full_name >>> have been removed. These probably don't serve an useful purpose, as the user >>> of this API need to know anyway what properties are specific to the device he >>> wants to access with VFIO. If we decide to reintroduce the list of properties >>> in the future, the generic device properties API in the kernel will have to >>> be extended accordingly. >>> >>> A kernel with this series and all the dependencies applied can be pulled from >>> branch vfio-device-properties-v3 from the repository: >>> https://github.com/virtualopensystems/linux-kvm-arm.git >>> >>> Changes since v2: >>> - Reworked on top of Rafael J. Wysocki's uniform device properties API for >>> device tree and ACPI >>> - Support for u64 array properties >>> - Removed API to get list of available properties and device tree full_name >>> Changes since v1: >>> - Updated for VFIO platform patch series v8: >>> VFIO AMBA devices now supported in addition to VFIO PLATFORM devices >>> - Refactored and cleaned up the code >>> >>> Antonios Motakis (3): >>> vfio: platform: add device properties skeleton and user API >>> vfio: platform: access device property as a list of strings >>> vfio: platform: return device properties as arrays of unsigned >>> integers >>> >>> drivers/vfio/platform/Makefile | 3 +- >>> drivers/vfio/platform/properties.c | 162 ++++++++++++++++++++++++++ >>> drivers/vfio/platform/vfio_platform_common.c | 35 ++++++ >>> drivers/vfio/platform/vfio_platform_private.h | 7 ++ >>> include/uapi/linux/vfio.h | 26 +++++ >>> 5 files changed, 232 insertions(+), 1 deletion(-) >>> create mode 100644 drivers/vfio/platform/properties.c >>> >> > > > _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
