Date: Fri, 1 Apr 2016 12:48:24 -0400 From: Ryan Stone <rysto32@gmail.com> To: John Baldwin <jhb@freebsd.org> Cc: Luigi Rizzo <rizzo@iet.unipi.it>, Jim Harris <jim.harris@gmail.com>, FreeBSD Current <freebsd-current@freebsd.org>, Giuseppe Lettieri <g.lettieri@iet.unipi.it>, Vincenzo Maffione <v.maffione@gmail.com> Subject: Re: accessing a PCIe register from userspace through kmem or other ways ? Message-ID: <CAFMmRNxJDuQoC-YuwbaWkj7MGVw9UgPEANOX6bN=i8%2Bp_9vm5w@mail.gmail.com> In-Reply-To: <5045119.GKNSyI10vh@ralph.baldwin.cx> References: <CA%2BhQ2%2BiU4odjhaNicFA4QjvSZR2OZOOy%2BFu4LTqsibdoK4M8zg@mail.gmail.com> <CAFMmRNxCHgRD4bUWwZiG%2B6HiLD2DxagFgHTGmH5jtRj%2BUEtJNA@mail.gmail.com> <CA%2BhQ2%2BjeyVFp-bHckuLtBQ1VBkk%2BA86EvUyC%2BCB2ZZFiye6k1g@mail.gmail.com> <5045119.GKNSyI10vh@ralph.baldwin.cx>
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On Fri, Apr 1, 2016 at 12:31 PM, John Baldwin <jhb@freebsd.org> wrote: > Sorry, I mapped PCIe registers to the PCI-e config space register set. I > am > not sure exactly how libpciaccess handles register access (perhaps it reads > raw bars and maps them via /dev/mem)? However, it would not be hard to a > new ioctl to /dev/pci to allow one to mmap a specific BAR of a given > device. > That is actually a really good question. I know that with some recent BIOSes if I enabled allocating 64-bit addresses to BARs, the BAR would actually be mapped outside of the range of /dev/mem. From a quick glance at libpciaccess, I don't think that it handles this case. A specific mechanism for allowing mmaping of BARs would be useful, I think.
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