s390/ipl: add support to control memory clearing for FCP and CCW re-IPL

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Re-IPL for both CCW and FCP is currently done by using diag 308 with the
"Load Clear" subcode, which means that all memory will be cleared.
This can increase re-IPL duration considerably on very large machines.

For CCW devices, there is also a "Load Normal" subcode that was only used
for dump kernels so far. For FCP devices, a similar "Load Normal" subcode
was introduced with z14. The "Load Normal" diag 308 subcode allows to
re-IPL without clearing memory.

This patch adds a new "clear" sysfs attribute to /sys/firmware/reipl for
both the ccw and fcp subdirectories, which can be set to either "0" or "1"
to disable or enable re-IPL with memory clearing. The default value is "0",
which disables memory clearing.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

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This commit is contained in:

Gerald Schaefer 2020-02-20 16:22:30 +01:00 • committed by Vasily Gorbik

parent 40501c70e3

commit 1a2ae03b19

2 changed files with 67 additions and 7 deletions

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arch/s390/include/asm/ipl.h

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73

arch/s390/kernel/ipl.c

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