From mboxrd@z Thu Jan 1 00:00:00 1970 From: walter harms Subject: Re: [patch] perf_event_open.2 -- expand ERRORS section Date: Wed, 16 Apr 2014 09:18:34 +0200 Message-ID: <534E2ECA.5030605@bfs.de> References: <5346F5EC.6080600@gmail.com> <534BBC07.7040105@gmail.com> Reply-To: wharms-fPG8STNUNVg@public.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-man-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Vince Weaver Cc: linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-man@vger.kernel.org Am 15.04.2014 20:25, schrieb Vince Weaver: > On Mon, 14 Apr 2014, Michael Kerrisk (man-pages) wrote: >=20 >> >> EACCES Returned when the requested event requires root permi= s=E2=80=90 >> sions (or a more permissive perf_event paranoid se= t=E2=80=90 >> ting). Some common cases where an unprivileged proce= ss >> may encounter this error: are attaching to a proce= ss >> owned by a different user; monitoring all processes on= a >> given CPU; and not setting exclude_kernel when the par= a=E2=80=90 >> noid setting requires it. >> >> But, now I have some more questions: >> >> * What are "root permissions" here? It's these days usual to express >> things precisely in terms of the required capability. >=20 > Yes, I guess that should really be CAP_SYS_ADMIN >=20 >> * I am puzzled by "monitoring all processes on a CPU"? So, monitorin= g=20 >> _some_ (i.e., < all) processes on a CPU won't trigger this error? >=20 > I was a bit confused here. >=20 > A regular user can monitor "the specified process on CPU X" or "the=20 > specified process on any CPU". >=20 > A user running as root can also monitor "all procceses belonging to a= nyone=20 > on CPU X" >=20 why not "can monitor any process" ? re, wh > Other combinations aren't possible. >=20 >>>>> +.B EPERM >>>>> +Returned if sufficient permissions not available to create the e= vent. >> >> Again, somewhere here, the text should mention the required capabili= ty. >=20 > Yes, it's CAP_SYS_ADMIN again. >=20 >>> This is a recent change. =20 >> >> So, the text should mention a kernel version number. Could you patch= =20 >> that please. I guess it should be something like: >> >> and (since Linux 3.??) setting an ftrace function-trace tracepoi= nt >=20 > Yes, I'll do that. >=20 > Vince -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html