Re: [PATCH v7 20/21] PCI/P2PDMA: Introduce pci_mmap_p2pmem()

Christoph Hellwig
2022-07-05T16:12:48Z

On Tue, Jul 05, 2022 at 10:51:02AM -0300, Jason Gunthorpe wrote:
> > In fact I'm not even sure this should be a character device, it seems
> > to fit it way better with the PCI sysfs hierchacy, just like how we
> > map MMIO resources, which these are anyway. And once it is on sysfs
> > we do have a uniqueue inode and need none of the pseudofs stuff, and
> > don't need all the glue code in nvme either.
>
> Shouldn't there be an allocator here? It feels a bit weird that the
> entire CMB is given to a single process, it is a sharable resource,
> isn't it?

Making the entire area given by the device to the p2p allocator available
to user space seems sensible to me. That is what the current series does,
and what a sysfs interface would do as well.