From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Kerrisk Subject: Re: proc(5): /proc/[number]/cmdline explanation update Date: Thu, 14 Feb 2008 19:54:20 +0100 Message-ID: <47B48E5C.2080108@gmail.com> References: <1202278450.3897.32.camel@sebastian.kern.oss.ntt.co.jp> <47B0780D.2090501@gmail.com> <1202795266.22621.16.camel@sebastian.kern.oss.ntt.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <1202795266.22621.16.camel-xpvPi5bcW5X5OjGIXfuPlhrrLbDL3r4M6qtp775pBPw@public.gmane.org> Sender: linux-man-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: =?ISO-8859-1?Q?Fernando_Luis_V=E1zquez_Cao?= Cc: Michael Kerrisk , linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-man@vger.kernel.org =46ernando Luis V=E1zquez Cao wrote: > Hi Michael, >=20 > It seems the old description applies to all 2.0, 2.2, and 2.3 kernels= up > to and including 2.3.26. After that the behavior changed as explained= in > my patch. Thanks. Patch applied for man-pages-2.79. Cheers, Michael > Fernando >=20 > On Mon, 2008-02-11 at 17:30 +0100, Michael Kerrisk wrote: >> Fernando, >> >> Do you know when (which kernel version) this change in behavior occu= rred? >> >> Cheers, >> >> Michael >> >> Fernando Luis V=E1zquez Cao wrote: >>> It used to be true that the command line arguments were not accessi= ble >>> when the process had been swapped out. In ancient kernels (circa 2.= 0.*) >>> the problem was that the kernel relied on get_phys_addr to access t= he >>> user space buffer, which stopped working as soon as the process was >>> swapped out. Recent kernels use get_user_pages for the same purpose= and >>> thus they should not have that limitation. >>> >>> Signed-off-by: Fernando Luis Vazquez Cao >>> --- >>> >>> --- proc.5.orig 2008-02-06 14:11:58.000000000 +0900 >>> +++ proc.5 2008-02-06 14:56:22.000000000 +0900 >>> @@ -87,12 +87,11 @@ plus one \fIunsigned long\fP value for e >>> The last entry contains two zeros. >>> .TP >>> .I /proc/[number]/cmdline >>> -This holds the complete command line for the process, unless the w= hole >>> -process has been swapped out or the process is a zombie. >>> -In either of these latter cases, there is nothing in this file: >>> -that is, a read on this file will return 0 characters. >>> -The command line arguments appear in this file as a set of >>> -null-separated strings, with a further null byte after the last st= ring. >>> +This holds the complete command line for the process, unless the p= rocess is a >>> +zombie. In the latter case, there is nothing in this file: that is= , a read on >>> +this file will return 0 characters. The command line arguments app= ear in this >>> +file as a set of null-separated strings, with a further null byte = after the >>> +last string. >>> .TP >>> .I /proc/[number]/cwd >>> This is a symbolic link to the current working directory of the pr= ocess. >>> >>> >>> >=20 >=20 --=20 Michael Kerrisk Maintainer of the Linux man-pages project http://www.kernel.org/doc/man-pages/ Want to report a man-pages bug? Look here: http://www.kernel.org/doc/man-pages/reporting_bugs.html