On Tuesday 05 August 2008 18:51, James Bottomley wrote: > On Tue, 2008-08-05 at 14:40 +0200, Martin Petermann wrote: > > 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 <davidw@xxxxxxxxxx> > > 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. > > First of all, why is the device returning PQ=1 PTD=0x1f? this should > mean its not connected and probably doesn't exist... ie inaccessible > without some unspecified action being taken. If you can use it, it's > clearly not behaving like a PQ=1 LUN. Perhaps the simplest thing would > be for something in s390 to fix up the inquiry data ... or we could > allow you could have a script to force it to appear (as in if you send a > specific scan for this one LUN we could override the catch in the code > that throws it out again). > > James > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > James I think Martin is saying that this LUN is a non existent one which is just used for scanning all available (existing) LUNs on the remote storage port. That's why PQ=1 PTD=0x1f are returned and correct ! So what's required here is the possibility to add a "dummy" LUN which can be used just for this purpose. Not sure whether this is covered by anything in the standard Cheers Swen -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
