Date: Fri, 1 Apr 2016 13:07:55 +0200 From: Luigi Rizzo <rizzo@iet.unipi.it> To: Ryan Stone <rysto32@gmail.com>, Jim Harris <jim.harris@gmail.com> Cc: John Baldwin <jhb@freebsd.org>, 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: <CA%2BhQ2%2BjeyVFp-bHckuLtBQ1VBkk%2BA86EvUyC%2BCB2ZZFiye6k1g@mail.gmail.com> In-Reply-To: <CAFMmRNxCHgRD4bUWwZiG%2B6HiLD2DxagFgHTGmH5jtRj%2BUEtJNA@mail.gmail.com> References: <CA%2BhQ2%2BiU4odjhaNicFA4QjvSZR2OZOOy%2BFu4LTqsibdoK4M8zg@mail.gmail.com> <CAJP=Hc_A2-i8twW4AhnA50ryf3%2BHLOparQ9xcCnCCVLv0%2B9PSw@mail.gmail.com> <2550091.UENsv0ilXD@ralph.baldwin.cx> <CAFMmRNxCHgRD4bUWwZiG%2B6HiLD2DxagFgHTGmH5jtRj%2BUEtJNA@mail.gmail.com>
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On Thu, Mar 31, 2016 at 11:55 PM, Ryan Stone <rysto32@gmail.com> wrote: > On Thu, Mar 31, 2016 at 4:39 PM, John Baldwin <jhb@freebsd.org> wrote: > >> On Wednesday, March 30, 2016 11:20:51 AM Jim Harris wrote: >> > On Wed, Mar 30, 2016 at 10:47 AM, Luigi Rizzo <rizzo@iet.unipi.it> >> wrote: >> > >> > > Hi, >> > > I'd like to test the rate at which I can access device registers >> > > on a PCIe card, and was wondering whether I need to patch a device >> > > driver, or perhaps I can use /dev/kmem once I figure out where >> > > the registers are mapped ? >> > > >> > >> > You do not need to patch a device driver. Have you looked at >> > libpciaccess? This should give you everything you need. >> >> You can also look at what pciconf uses. (It has a read_config() method >> that uses an ioctl on an fd of /dev/pci). >> > > pciconf can only access the configuration space, right? I believe that > Luigi is more interested in measuring the latency to a register mapped fr= om > a BAR. > =E2=80=8BThank you all for you answers, I will look at libpciaccess. Yes my goal is to look at the rate and latency for accessing BAR-mapped registers cheers luigi=E2=80=8B --=20 -----------------------------------------+------------------------------- Prof. Luigi RIZZO, rizzo@iet.unipi.it . Dip. di Ing. dell'Informazione http://www.iet.unipi.it/~luigi/ . Universita` di Pisa TEL +39-050-2217533 . via Diotisalvi 2 Mobile +39-338-6809875 . 56122 PISA (Italy) -----------------------------------------+-------------------------------
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