Documentation/arch/s390/monreader.rst

Source file repositories/reference/linux-study-clean/Documentation/arch/s390/monreader.rst

File Facts

System
Linux kernel
Corpus path
Documentation/arch/s390/monreader.rst
Extension
.rst
Size
8628 bytes
Lines
213
Domain
Support Tooling And Documentation
Bucket
Documentation
Inferred role
Support Tooling And Documentation: documentation
Status
atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

=================================================
Linux API for read access to z/VM Monitor Records
=================================================

Date  : 2004-Nov-26

Author: Gerald Schaefer (geraldsc@de.ibm.com)




Description
===========
This item delivers a new Linux API in the form of a misc char device that is
usable from user space and allows read access to the z/VM Monitor Records
collected by the `*MONITOR` System Service of z/VM.


User Requirements
=================
The z/VM guest on which you want to access this API needs to be configured in
order to allow IUCV connections to the `*MONITOR` service, i.e. it needs the
IUCV `*MONITOR` statement in its user entry. If the monitor DCSS to be used is
restricted (likely), you also need the NAMESAVE <DCSS NAME> statement.
This item will use the IUCV device driver to access the z/VM services, so you
need a kernel with IUCV support. You also need z/VM version 4.4 or 5.1.

There are two options for being able to load the monitor DCSS (examples assume
that the monitor DCSS begins at 144 MB and ends at 152 MB). You can query the
location of the monitor DCSS with the Class E privileged CP command Q NSS MAP
(the values BEGPAG and ENDPAG are given in units of 4K pages).

See also "CP Command and Utility Reference" (SC24-6081-00) for more information
on the DEF STOR and Q NSS MAP commands, as well as "Saved Segments Planning
and Administration" (SC24-6116-00) for more information on DCSSes.

1st option:
-----------
You can use the CP command DEF STOR CONFIG to define a "memory hole" in your
guest virtual storage around the address range of the DCSS.

Example: DEF STOR CONFIG 0.140M 200M.200M

This defines two blocks of storage, the first is 140MB in size an begins at
address 0MB, the second is 200MB in size and begins at address 200MB,
resulting in a total storage of 340MB. Note that the first block should
always start at 0 and be at least 64MB in size.

2nd option:
-----------
Your guest virtual storage has to end below the starting address of the DCSS
and you have to specify the "mem=" kernel parameter in your parmfile with a
value greater than the ending address of the DCSS.

Example::

	DEF STOR 140M

This defines 140MB storage size for your guest, the parameter "mem=160M" is
added to the parmfile.


User Interface
==============
The char device is implemented as a kernel module named "monreader",
which can be loaded via the modprobe command, or it can be compiled into the
kernel instead. There is one optional module (or kernel) parameter, "mondcss",
to specify the name of the monitor DCSS. If the module is compiled into the
kernel, the kernel parameter "monreader.mondcss=<DCSS NAME>" can be specified
in the parmfile.

Annotation

Implementation Notes