Package: linux-kernel-di-s390-2.6 Version: 0.46 Severity: wishlist I am requesting that three additional kernel modules be added to the s390 version of the Debian Installer: vmcp, dasd_fba_mod, and dasd_diag_mod. I am assuming that vmcp belongs in core-modules-* and the other two belong in dasd-modules-*; but it is up to you how you want to package it.
When used as a pure installer to install on CKD DASD, these modules are not needed. However, when used in a "rescue-like" mode to perform system maintenance, such as copying data to CMS-format disks, these modules are very useful. When running in a virtual machine under z/VM, vmcp allows the root user to issue commands to the CP component of z/VM, the hypervisor which manages the configuration of the virtual machine that Linux is running in. For example, the LINK or DETACH commands can be issued to dynamically add disks to or remove disks from the environment. vmcp is not essential. The alternative is to issue CP commands via "#CP" on the 3215 virtual console. But vmcp is a great convenience as it allows CP commands to be issued from, for example, a remote SSH client session. dasd_fba_mod is essential to support FBA DASD. The only disk format supported by the Linux kernel for use on FBA DASD is the CMS disk format, and parted doesn't support the CMS disk format. Therefore, the installer cannot install to FBA DASD. But data can be copied to FBA DASD after installation to CKD DASD. However, when attempting to use the installer in a rescue-like mode for this purpose, FBA DASD cannot be used, since there is no dasd_fba_mod kernel module. dasd_diag_mod is necessary when using the DIAG driver, which can be used with either CKD DASD or FBA DASD. With CKD DASD, support for the DIAG driver can be enabled after the fact. But according to "Device Drivers, Features, and Commands, Development Stream (Kernel 2.6.32)", SC33-8411-04, Chapter 3, DASD Device Driver, under the heading "Enabling DIAG calls to access DASDs", the DIAG driver must be in use from the beginning when it is used with FBA DASD. I quote: Note: When switching between enabled and disabled DIAG calls on FBA-type DASD, first re-initialize the DASD, for example, with CMS format or by overwriting any previous content. Switching without initialization might cause data-integrity problems. If the goal is to use the DIAG driver to access data on an FBA DASD, then the DIAG driver must be used from the beginning when making a file system or swap space. Thus, when used in a rescue-like mode to perform this type of system maintenance, kernel module dasd_diag_mod must be available. I run the "generic" version of the installer, IPLed from the virtual card reader in a virtual machine under z/VM by running the "DEBIAN EXEC" script under the CMS operating system. The way I use the installer to do this type of maintenance is to run the installer in expert mode (debconf/priority=low), run all the steps of the installation up through and including the display of the existing partitions on the existing DASD, exit this menu without making any partition changes or assigning mount points, (<Go Back>) and drop into a shell. At that point, modprobe commands on vmcp, dasd_fba_mod, and dasd_diag_mod all fail. I do not run in true rescue mode (i.e. the rescue/enable=true boot parameter is not set) because I do not want the installer to attempt to mount my normal root partition as "/". I want to copy that partition and chroot to the copy later. Once I am finished with my maintenance activities, I type "exit" to return to the installer menu, then I select "Abort the installation" to shut down. An example procedure for copying data to CMS-format disks can be found at http://www.wowway.com/~zlinuxman/diag250.htm. The specific example here uses a separate server, but the procedure can be adapted to use the installer in a "rescue-like" mode, provided these three kernel modules are available. At present, they are not. -- To UNSUBSCRIBE, email to debian-boot-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
