Hi Christian. While at SLES9, would you recommend hcp be used instead of vmcp at least during boot? The Basevol/Guestvol script uses hcp, but since it sounded like vmcp was preferred over hcp, I changed the script to invoke vmcp instead.
I see udev in the boot process before the vmcp is issued (Basevol/Guestvol script). However, it is within 4 seconds. If it can take up to 10 seconds, it sounds like the timing of this not consistent enough at SLES9. 09:24:45 VFS: Mounted root (ext2 filesystem). Starting udev Creating devices 09:24:46 Loading kernel/drivers/s390/char/vmcp.ko z/VM CP interface loaded . . . 09:24:49 "" Basevol/Guestvol script begins... ."" Welcome to the Linux disk model userid!"" All directories will be in R/W mode."" Basevol/Guestvol script ends."" "" thanks again for your help. susan ---------------------------------------------------------------------- Date: Tue, 3 Jul 2007 09:30:58 +0200 From: Christian Borntraeger <[EMAIL PROTECTED]> Subject: Re: vmcp during boot results in Error: Could not open device /dev/vmcp: No such device Am Montag, 2. Juli 2007 schrieb Susan Zimmerman: > Hi Mark. >=20 > I noticed /sys/class/misc/vmcp was 10 63 >=20 > OSA-LNX1:~ # cat /sys/class/misc/vmcp/dev > 10:63 >=20 > So I deleted /dev/vmcp and manually created the node >=20 > as 10 63 >=20 > and now it works just fine. >=20 > Thanks for your help. Yes, vmcp registers a misc device with dynamic minor number. Therefore it i= s=20 normally not a good idea to have a permanent device node for vmcp, unless y= ou=20 know the load sequence of all your misc devices. Instead udev should be use= d.=20 I know that this is getting trickier on an initrd.=20 There is a problem assigned with udev: device node creation takes time. So= =20 after modprobe <module>, it can take some time to create a device node.=20 (usually milliseconds, but it can take longer) Udev has improved a lot on SLES10 and RHEL5. On these systems you can=20 use "udevsettle" to be sure that udev has finished all its work that was=20 scheduled until now: # modprobe vmcp # udevsettle # vmcp my fancy command will always work as long as the kernel module was able to load. Furthermore= ,=20 both systems use a tmpfs filesystem as /dev so your device folder is=20 re-initialized during boot without stale device nodes.=20 Things are much trickier on SLES9 and RHEL4. Both use an older udev version= =20 without udevsettle. SLES9 does not use tmpfs. SLES9 also does not use udev for devices, which=20 exist during boot, unless you enable the boot.udev init script.=20 RHEL4 uses udev for all devices, but has another issue. There is a race in = the=20 network hotplug scripts (I forgot the bugzilla number). In these script,=20 hotplug is temporarily disabled and udev can loose events. If udev misses a= n=20 event it will wait up to 10 seconds until it continues. Thats why on=20 RHEL4 "modprobe vmcp -> /dev/vmcp appears" will often take 10 seconds. =2D-=20 IBM Deutschland Entwicklung GmbH Vorsitzender des Aufsichtsrats: Martin Jetter Gesch=E4ftsf=FChrung: Herbert Kircher=20 Sitz der Gesellschaft: B=F6blingen Registergericht: Amtsgericht Stuttgart, HRB 243294 ---------------------------------------------------------------------- ---------------------------------------------------------------------- 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
