Thanks, Mack for that bit of enlightenment. I figured it was magic - just didn't know whether it was black magic - or big Blue.
Roger On Fri, 2010-11-05 at 11:07 -0400, Edmund R. MacKenty wrote: > On Friday, November 05, 2010 09:37:35 am you wrote: > > I just cut and pasted into my startup script from the readme file at > > > > http://www-01.ibm.com/support/docview.wss?uid=swg27006164 > > > > to wit: > > ¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨ > > Load the ctcmpc device driver > > > > # /sbin/modprobe ctcmpc > > Configure the read & write i/o device addresses for a ctcmpc device: > > # echo 0.0.0d90,0.0.0d91 > /sys/bus/ccwgroup/drivers/ctcmpc/group > > Set the ctcmpc device online: > > # echo 1 > /sys/bus/ccwgroup/drivers/ctcmpc/0.0.0d90/online > > ---------------------------- > > > > But I tried it with the quotes, and got the same result. > > The quotes are unnecessary, because there are no "shell-special" characters > in > that string to protect from betting changed by the shell. > > > This 'echo' command is strange. I wonder how it creates all these > > device files in /sys/bus/ccwgroup...? > > All the echo command does is copy its command line arguments to its standard > output. There's nothing strange about echo. The strangeness here is that > the > files in the /sys filesystem aren't really files: they're references to data > structures within the kernel. So when you write to > /sys/bus/ccwgroup/drivers/ctcmpc/group, you're not actually doing real file > I/O. Instead, the I/O call invokes a function within the CTC driver that > parses your two device numbers and builds the appropriate data structures > within the CTC driver to represent when as a paired device. Part of > generating the new data strutures involves registering entries for them with > the /sys filesystem and that causes those new file entries to appear under > /sys/bus/ccwgroup. > > That's the magic of the sysfs pseudo-filesystem: it is showing you > information > about the internal state of the kernel and letting you make certain changes > to > it. It's essentially a user-space interface to certain kernel-space data > structures. If you use CP to link a new device to a Linux guest, you'll see > sysfs entries for that device appear as the Linux driver detects the new > "hardware". > - MacK. > ----- > Edmund R. MacKenty > Software Architect > Rocket Software > 275 Grove Street - Newton, MA 02466-2272 - USA > Tel: +1.617.614.4321 > Email: [email protected] > Web: www.rocketsoftware.com > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO LINUX-390 or visit > http://www.marist.edu/htbin/wlvindex?LINUX-390 > ---------------------------------------------------------------------- > For more information on Linux on System z, visit > http://wiki.linuxvm.org/ Med vennlig hilsen Roger Evans Systemkonsulent ________________________________________________________________________ AutoData Norge AS - www.autodata.no - [email protected] Tlf: +47 23 17 20 30 Direkte: +47 23 17 20 46 - Faks: +47 23 17 20 50 ________________________________________________________________________ ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/
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