From: Nuno Das Neves <nunodasneves@xxxxxxxxxxxxxxxxxxx> Sent: Tuesday, October 22, 2024 5:51 PM > > On 10/10/2024 11:21 AM, Michael Kelley wrote: > > [snip] > > Have you considered user space code that uses > > include/linux/hyperv.h? Which of the two schemes will it use? That code > > needs to compile correctly on x86 and ARM64 after your changes. > > User space code includes the separate DPDK project, and some of the > > tools in the kernel tree under tools/hv. Anything that uses the > > uio_hv_generic.c driver falls into this category. > > > Unless I misunderstand something, the uapi code isn't affected at all > by this patch set. e.g. the code in tools/hv uses include/uapi/linux/hyperv.h, > which doesn't include any other Hyper-V headers. > > I'm not aware of how the DPDK project uses the Hyper-V definitions, but if it > is getting headers from uapi it should also be unaffected. You are right. My mistake. User space code based on uio_hv_generic.c maps the VMBus ring buffers into user space, and I thought that code was pulling "struct hv_ring_buffer" from include/linux/hyperv.h file. But DPDK and the tools/hv code each have their own completely separate header file with the equivalent of "struct hv_ring_buffer". Duplicating the ring buffer structure in multiple places probably isn't ideal, but the decoupling helps in this case. ;-) > > > I think there's also user space code that is built for vDSO that might pull > > in the .h files you are modifying. There are in-progress patches dealing > > with vDSO include files, such as [1]. My general comment on vDSO > > is to be careful in making #include file changes that it uses, but I'm > > not knowledgeable enough on how vDSO is built to give specific > > guidance. :-( > > > Hmm, interesting, looks like it does get used by userspace. The tsc page > is mapped into userspace in vdso.vma.c, and read in vdso/gettimeofday.h. > > That is unexpected for me, since these things aren't in uapi. However I don't > anticipate a problem. The definitions used haven't changed, just the headers > they are included from. > Fair enough. I don't know enough about vDSO user space to add anything helpful. Michael
