1. Feature Overview:
Feature Id: [67049]
a. Name of Feature: [6.1 FEAT] makedumpfile support - convert Linux on z dumps to ELF - userspace part
b. Feature Description
This feature allows to convert s390 format dumps into ELF format dumps. This is needed in order to
be able to use makedumpfile tool.

This feature has different parts needed and tracked in different feature depending on the affected
component (kernel, binutils, crash, s390-tools).

The port of makedumfile to s390 is tracked by a different feature.

This concrete feature provides the s390-tools part:
zgetdump:
Currently zgetdump is used to copy dumps from DASD and tape dump devices using the s390 dump format.
This feature adds two new dump formats, ELF (source/target) and LKCD (target). Therefore the
zgetdump tool can read ELF, s390 and LKCD and write ELF and s390 format dumps and now can also be
used for dump format conversion. The ELF target format can be used to run the "makedumpfile" tool
as a second step to compress the dump.
Also a mount option based on "fuse" will be added to zgetdump so that dumps can be converted in
memory without the need of copying them (see zgetdump man page below for more details).
Three new options are added to zgetdump:
??? fmt: Specify target dump format (elf or s390)
??? mount: Mount the dump instead of copying it to standard output
??? umount: Unmout the dump (wrapper function for "fusermount -u")
The "???all" option of zgetdump will be removed. The rational behind this is that this option is not
very useful, only applicable for multi-volume tape dumps that are very rare and technically with the
required new code structure of zgetdump it is a lot of effort to reimplement this option. The
decission is that it is not worth the effort.

DASD and Tape dump tools (zipl) and vmconvert:
The ELF format contains register information in the dump header. Currently for s390 dumps the
register information is stored in the CPU prefix pages in the dumped memory. The dump analysis tools
find these pages using the global variable "lowcore_ptr". In order to do this the memory address of
this variable must be available. The analysis tools crash and lcrash get that address from the
System.map or vmlinux file. To be independent from those files, with this item the s390 and LKCD
dump format is extended to store this information in the dump header.


2. Feature Details:
Sponsor: LTC zSeries BOE
Architectures:  zSeries - 64 native, 

Arch Specificity: purely arch specific code
Affects Kernel Modules: Field does not exist
Delivery Mechanism: Backport
Category: other
Request Type: Package - Feature from IBM
d. Upstream Acceptance: Field does not exist
Sponsor Priority P1
f. Severity: ship issue
IBM Confidential: No
Code Contribution: IBM code
g. Component Version Target:---

3. Business Case
The memory footprints of Linux on System z systems grow from year to year and therefore also system
dumps become sometimes so large that it is hard to work with them. For example transferring a 50 GB
dump over the network to a service organization can take a very long time. The "makedumpfile" open
source tool is used to compress system dumps by filtering out memory pages like free, user space or
cache pages that are not necessary for dump analysis.

This feature will improve and remove possible future restrictions in service, by enabling the
infrastructure needed to be able to use makedumfile on Linux on System z. 

4. Primary contact at Red Hat:
John Jarvis jjarvis

5. Primary contacts at Partner:
Project Management Contact:
Hans-Georg Markgraf, mgrf.com

Technical contact(s):
Gonzalo Muelas Serrano, gmuelas.com