Date: Thu, 31 Mar 2016 17:55:46 -0400 From: Ryan Stone <rysto32@gmail.com> To: John Baldwin <jhb@freebsd.org> Cc: FreeBSD Current <freebsd-current@freebsd.org>, Jim Harris <jim.harris@gmail.com>, Luigi Rizzo <rizzo@iet.unipi.it> Subject: Re: accessing a PCIe register from userspace through kmem or other ways ? Message-ID: <CAFMmRNxCHgRD4bUWwZiG%2B6HiLD2DxagFgHTGmH5jtRj%2BUEtJNA@mail.gmail.com> In-Reply-To: <2550091.UENsv0ilXD@ralph.baldwin.cx> References: <CA%2BhQ2%2BiU4odjhaNicFA4QjvSZR2OZOOy%2BFu4LTqsibdoK4M8zg@mail.gmail.com> <CAJP=Hc_A2-i8twW4AhnA50ryf3%2BHLOparQ9xcCnCCVLv0%2B9PSw@mail.gmail.com> <2550091.UENsv0ilXD@ralph.baldwin.cx>
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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 from a BAR.
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