Re: remove the nvlink2 pci_vfio subdriver v2
From: Daniel Vetter <hidden>
Date: 2021-05-04 14:23:47
Also in:
dri-devel, kvm, linux-api, lkml, qemu-devel
On Tue, May 04, 2021 at 03:20:34PM +0200, Greg Kurz wrote:
On Tue, 4 May 2021 14:59:07 +0200 Greg Kroah-Hartman [off-list ref] wrote:quoted
On Tue, May 04, 2021 at 02:22:36PM +0200, Greg Kurz wrote:quoted
On Fri, 26 Mar 2021 07:13:09 +0100 Christoph Hellwig [off-list ref] wrote:quoted
Hi all, the nvlink2 vfio subdriver is a weird beast. It supports a hardware feature without any open source component - what would normally be the normal open source userspace that we require for kernel drivers, although in this particular case user space could of course be a kernel driver in a VM. It also happens to be a complete mess that does not properly bind to PCI IDs, is hacked into the vfio_pci driver and also pulles in over 1000 lines of code always build into powerpc kernels that have Power NV support enabled. Because of all these issues and the lack of breaking userspace when it is removed I think the best idea is to simply kill. Changes since v1: - document the removed subtypes as reserved - add the ACK from Greg Diffstat: arch/powerpc/platforms/powernv/npu-dma.c | 705 --------------------------- b/arch/powerpc/include/asm/opal.h | 3 b/arch/powerpc/include/asm/pci-bridge.h | 1 b/arch/powerpc/include/asm/pci.h | 7 b/arch/powerpc/platforms/powernv/Makefile | 2 b/arch/powerpc/platforms/powernv/opal-call.c | 2 b/arch/powerpc/platforms/powernv/pci-ioda.c | 185 ------- b/arch/powerpc/platforms/powernv/pci.c | 11 b/arch/powerpc/platforms/powernv/pci.h | 17 b/arch/powerpc/platforms/pseries/pci.c | 23 b/drivers/vfio/pci/Kconfig | 6 b/drivers/vfio/pci/Makefile | 1 b/drivers/vfio/pci/vfio_pci.c | 18 b/drivers/vfio/pci/vfio_pci_private.h | 14 b/include/uapi/linux/vfio.h | 38 -Hi Christoph, FYI, these uapi changes break build of QEMU.What uapi changes?All macros and structure definitions that are being removed from include/uapi/linux/vfio.h by patch 1.
Just my 2cents from drm (where we deprecate old gunk uapi quite often): Imo it's best to keep the uapi headers as-is, but exchange the documentation with a big "this is removed, never use again" warning: - it occasionally serves as a good lesson for how to not do uapi (whatever the reasons really are in the specific case) - it's good to know which uapi numbers (like parameter extensions or whatever they are in this case) are defacto reserved, because there are binaries (qemu in this) that have code acting on them out there. The only exception where we completely nuke the structs and #defines is when uapi has been only used by testcases. Which we know, since we defacto limit our stable uapi guarantee to the canonical open&upstream userspace drivers only (for at least the driver-specific stuff, the cross-driver interfaces are hopeless). Anyway feel free to ignore since this might be different than drivers/gpu. Cheers, Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch