From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aaron Traas Subject: st ioctl documentation error (MT_ST_SYSV) Date: Sun, 13 Apr 2003 10:05:10 -0400 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <3E996E96.3040502@syncsort.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from pool-141-153-194-157.mad.east.verizon.net ([141.153.194.157]:60290 "EHLO claymore.tyrfing.org") by vger.kernel.org with ESMTP id S263517AbTDMN4x (for ); Sun, 13 Apr 2003 09:56:53 -0400 Received: from rapier.tyrfing.org ([10.1.1.166] helo=syncsort.com) by claymore.tyrfing.org with esmtp (Exim 3.35 #1 (Debian)) id 194i9o-0004Rm-00 for ; Sun, 13 Apr 2003 10:08:33 -0400 List-Id: linux-scsi@vger.kernel.org To: linux-scsi@vger.kernel.org Hello. I'm trying to fix some bugs in a port of my company's proprietar= y=20 tape backup software. Our software works flawlessly on most commercial=20 UNIX platforms. When handling tape reads, we use one of two different=20 subroutines for handling the positioning of the read-head after a read.= =20 On BSD-flavored systems (such as *BSD), we do more-or-less nothing, as=20 after a read, the tape is spaced forward to the next filemark. On SysV=20 flavored systems (like Solaris 8), we advance the filemark manually. We have a problem on Linux, as it states in the st(4) manpage: MT_ST_SYSV (Default: false) When this option is enabled, the tape devices use the SystemV semantics. Other=AD wise the BSD semantics are used. The most important difference between the semantics is what happens when a device used for reading is closed: in SYSV semantics the tape is spaced forward past the next file=AD mark if this has not happened while using the device. In BSD semantics the tape posi=AD tion is not changed. Which switches what we have defined as BSD and SYSV semantics. It state= s=20 that Linux uses BSD semantics by default, and then says SYSV semantics=20 are what we know are BSD semantics, and that BSD semantics are what we=20 know as SYSV semantics. How do we know? BSD and Solaris' man pages on=20 the subject contradict Linux's, and our software properly works on thos= e=20 systems. So, going by the description in the page on what the semantics are, we=20 have defined Linux in our build system as using non-BSD style tape read= =20 semantics. This results in fsf errors. - To unsubscribe from this list: send the line "unsubscribe linux-scsi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html