path: root/sbin/savecore/savecore.8
diff options
authorMark Johnston <markj@FreeBSD.org>2017-10-25 00:51:00 +0000
committerMark Johnston <markj@FreeBSD.org>2017-10-25 00:51:00 +0000
commit64a16434d8dbd5432e2f1a49007e53a449d43830 (patch)
treee9cdb0a8780646580c9a0d35fd94332c6a2443ad /sbin/savecore/savecore.8
parent7b79d6d61ac82b21e2acc396a4ea66d0e92c79d9 (diff)
Add support for compressed kernel dumps.
When using a kernel built with the GZIO config option, dumpon -z can be used to configure gzip compression using the in-kernel copy of zlib. This is useful on systems with large amounts of RAM, which require a correspondingly large dump device. Recovery of compressed dumps is also faster since fewer bytes need to be copied from the dump device. Because we have no way of knowing the final size of a compressed dump until it is written, the kernel will always attempt to dump when compression is configured, regardless of the dump device size. If the dump is aborted because we run out of space, an error is reported on the console. savecore(8) is modified to handle compressed dumps and save them to vmcore.<index>.gz, as it does when given the -z option. A new rc.conf variable, dumpon_flags, is added. Its value is added to the boot-time dumpon(8) invocation that occurs when a dump device is configured in rc.conf. Reviewed by: cem (earlier version) Discussed with: def, rgrimes Relnotes: yes Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D11723
Notes: svn path=/head/; revision=324965
Diffstat (limited to 'sbin/savecore/savecore.8')
1 files changed, 6 insertions, 2 deletions
diff --git a/sbin/savecore/savecore.8 b/sbin/savecore/savecore.8
index 45e2af9588b3..ae2265070b85 100644
--- a/sbin/savecore/savecore.8
+++ b/sbin/savecore/savecore.8
@@ -28,7 +28,7 @@
.\" From: @(#)savecore.8 8.1 (Berkeley) 6/5/93
.\" $FreeBSD$
-.Dd December 10, 2016
+.Dd October 24, 2017
@@ -96,8 +96,12 @@ the counter will restart from
Print out some additional debugging information.
Specify twice for more information.
.It Fl z
-Compress the core dump and kernel (see
+Compress the dump (see
.Xr gzip 1 ) .
+The dump may already be compressed if the kernel was configured to
+do so by
+.Xr dumpon 8 .
+In this case, the option has no effect.