On 3/22/2017 10:18 AM, Will Deacon wrote: > On Wed, Mar 22, 2017 at 10:15:04AM -0400, Sinan Kaya wrote: >> On 3/22/2017 10:04 AM, David Woodhouse wrote: >>> On Wed, 2017-03-22 at 09:54 -0400, Sinan Kaya wrote: >>>> On 3/22/2017 9:25 AM, David Woodhouse wrote: >>>>> >>>>> >>>>> +#ifdef __aarch64__ >>>>> +/* ARM64 wants to be special and not expose this through /proc >>>>> like everyone else */ >>>>> +#undef HAVE_PCI_MMAP >>>>> +#endif >>>>> + >>>> Where is this ARM64 special requirement coming from? >>> >>> The idea is that as a new platform, ARM64 shouldn't need to implement >>> legacy userspace interfaces. >>> >>> http://lists.infradead.org/pipermail/linux-arm-kernel/2016-April/422571.html >>> >> >> Aren't we breaking an ABI for userspace? I know DPDK relies on this feature. > > It relies on the /proc interface? That's the first I've ever heard of that > -- everybody so far has only been interested in the sysfs stuff. > > Nothing's more broken than before, because we've never supported the /proc > interface, but if existing arm64 code out there is failing because of that > then I'm of course open to supporting it. I'm just surprised that nobody > else has come up with that before, since DPDK is in common use. > > Can you point me at the specific code, please? I'm correcting myself. I had to go back my memory from last year. DPDK requires HAVE_PCI_MMAP to be set. We have been carrying some old maillist patch around for DPDK customers internally. When HAVE_PCI_MMAP is set, resource files are created in sysfs and procfs. DPDK is using the files in sysfs directory not procfs directory. Having HAVE_PCI_MMAP defined is the DPDK requirement. > > Will > -- Sinan Kaya Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
