From mboxrd@z Thu Jan 1 00:00:00 1970 From: Martin Petermann Subject: With kernel 2.6.19 no sg devices for devices that return PQ=1, PDT=0x1f Date: Tue, 05 Aug 2008 14:40:00 +0200 Message-ID: <48984A20.2050002@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mtagate6.de.ibm.com ([195.212.29.155]:50312 "EHLO mtagate6.de.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757257AbYHENGb (ORCPT ); Tue, 5 Aug 2008 09:06:31 -0400 Received: from d12nrmr1607.megacenter.de.ibm.com (d12nrmr1607.megacenter.de.ibm.com [9.149.167.49]) by mtagate6.de.ibm.com (8.13.8/8.13.8) with ESMTP id m75CdHTG578544 for ; Tue, 5 Aug 2008 12:39:17 GMT Received: from d12av03.megacenter.de.ibm.com (d12av03.megacenter.de.ibm.com [9.149.165.213]) by d12nrmr1607.megacenter.de.ibm.com (8.13.8/8.13.8/NCO v9.0) with ESMTP id m75CdHnF4259978 for ; Tue, 5 Aug 2008 14:39:17 +0200 Received: from d12av03.megacenter.de.ibm.com (loopback [127.0.0.1]) by d12av03.megacenter.de.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m75CdGra016629 for ; Tue, 5 Aug 2008 14:39:17 +0200 Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: linux-scsi@vger.kernel.org With kernel 2.6.19 a change was introduced that no sg device was generated if PQ=1, PDT=0x1f was returned from the particular device: commit 84961f28e9d13a4b193d0c8545f3c060c1890ff3 Author: dave wysochanski Date: Wed Aug 9 14:56:32 2006 -0400 [SCSI] Don't add scsi_device for devices that return PQ=1, PDT=0x1f Before it was possible on Linux 390 in user space to a e.g. LUN 0 to a port and to receive a generic device: t6345056:/sys/bus/ccw/devices/0.0.5922/0x500507630313c562 # ll total 0 -r--r--r-- 1 root root 4096 Aug 4 12:07 access_denied -rw-r--r-- 1 root root 4096 Aug 4 12:07 failed -r--r--r-- 1 root root 4096 Aug 4 12:07 in_recovery -r--r--r-- 1 root root 4096 Aug 4 12:07 status --w------- 1 root root 4096 Aug 4 12:07 uevent --w------- 1 root root 0 Aug 4 13:46 unit_add --w------- 1 root root 0 Aug 5 14:24 unit_remove t6345056:/sys/bus/ccw/devices/0.0.5922/0x500507630313c562 # echo 0 > unit_add t6345056:/sys/bus/ccw/devices/0.0.5922/0x500507630313c562 # ll total 0 drwxr-xr-x 2 root root 0 Aug 5 14:25 0x0000000000000000 -r--r--r-- 1 root root 4096 Aug 4 12:07 access_denied -rw-r--r-- 1 root root 4096 Aug 4 12:07 failed -r--r--r-- 1 root root 4096 Aug 4 12:07 in_recovery -r--r--r-- 1 root root 4096 Aug 4 12:07 status --w------- 1 root root 4096 Aug 4 12:07 uevent --w------- 1 root root 0 Aug 5 14:25 unit_add --w------- 1 root root 0 Aug 5 14:24 unit_remove t6345056:/sys/bus/ccw/devices/0.0.5922/0x500507630313c562 # lsscsi -g [0:0:0:0] no dev IBM 2107900 2.27 - /dev/sg0 After this fix there is no /dev/sg0 device generated. We are utilizing the possibility to create such a device for the sg_utils commands in the case no other LUN has been attached to a port. I do not want to put this fix into question. I would like to know if someone has an idea how to workaround this problem and to generate a generic device in user space using kernel 2.6.19 or a later version. Regards Martin