Currently kdump is not working well with encrypted targets, add document
about this issue.
Signed-off-by: Kairui Song <kasong@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
Add some note about the limitation of kdumpctl's auto detect and rebuild
feature, and suggest the user to rebuild the initramfs manually on
major system change, and don't include the initramfs in disk images.
Put the note about system change in front part of the document so user
will less likely to miss it.
Signed-off-by: Kairui Song <kasong@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
kdumpctl fails to load a crash kernel if KASLR is enabled.
The incorrect configuration of the kptr_restrict parameter causes that
the kdumpctl fails to load a crash kernel. The problem occurs when the
Kernel Address Space Layout Randomization (KASLR) mechanism is enabled.
The value of kptr_restrict decides how to expose the content of /proc
files. Inappropriate setting will cause that the /proc/kallsyms file is
being printed as all zeros. This configuration will break the kdump
loading process since it needs access to the conntent of /proc/kallsyms
if KASLR is enabled.
Set kptr_restrict to 1 to avoid the problem described above.
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
In preparation for adding 'final_action' option, since it's confusing
to have the 'final_action' and 'default' options at the same time,
this patch introduces 'failure_action' as an alias of the 'default'
option to /etc/kdump.conf, and makes 'default' obsolete to be removed
in the future.
Also, the "default action" term is renamed to "failure action".
Signed-off-by: Kazuhito Hagio <k-hagio@ab.jp.nec.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Lianbo Jiang <lijiang@redhat.com>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Acked-by: Bhupesh Sharma <bhsharma@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Kairui Song <kasong@redhat.com>
Update "kexec-kdump-howto" to illustrate the usage of special mount
information via "dracut_args".
Reviewed-by: Pratyush Anand <panand@redhat.com>
Suggested-by: Dave Young <dyoung@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Xunlei Pang <xlpang@redhat.com>
Update howto with notes on dracut and kernel watchdog module handling.
Signed-off-by: Pratyush Anand <panand@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
Add descriptions of parallel dumping and how to use it.
Signed-off-by: Zhou Wenjian <zhouwj-fnst@cn.fujitsu.com>
Reviewed-by: Pratyush Anand <panand@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
Previously /boot is asumed as the default dir where kernel and initrd
is put. However, the directory containing the running kernel image
on Atomic systems differs in each installation. Usually something like:
/boot/ostree/rhel-atomic-host-b50a015b637c353dc6554c851f8a1212b60d6121a7316715e4a63e2a4113cd72
This means that kdump will not find vmlinuz when installed on an
Atomic host, and thus the kdump service will fail to start.
In this patch, the kdump boot dir finding behaviour is a little changed.
Firstly check whether user has specify a directory explicitly in
/etc/sysconfig/kdump. If yes that is respected. Otherwise we assume
1st kernel and kdump kernel are put in the same place under /boot.
Then find it according /proc/cmdline and append it to /boot/
Note:
So now the KDUMP_BOOTDIR in /etc/sysconfig/kdump is set as empty
by default. If user set KDUMP_BOOTDIR to a directory, then he need to
take care of all related things himself. otherwise kdump script handle
it automatically.
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
Acked-by: Minfei Huang <mhuang@redhat.com>
In case no target is specified explicitly in /etc/kdump.conf, the behavior
of path is changed, a check need be taken to see if any separate file
system is mounted on any tier of 'path', and also to take the relevant
action. Now the path section need be renewed accordingly.
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Lzo is proven faster than zlib, for large memory machine it will
extremely shorten the time for saving vmcore. Let's switch to lzo as the
default compression method for makedumpfile.
The drawback is lzo has a little less compression ratio than zlib. But
considering for most users, speed/time is a more serious concern than
vmcore size. So I think default to lzo will benefit most of the users.
v1->v2: update kdump.conf.5 [DaveY]
Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
Add a section for debugging tips. I had to spend some time to figure out
how to drop into a shell from kdump_pre/kdump_post scripts. So thought of
documenting that so that somebdoy else can save time.
Also add a method to log serial consoles for virtual machines. I was
loosing some of the messages over reboot. Logging to file is fine. This
can be helful in debugging.
v2: Add method to log serial console for virtual machines
v3: Fix serial console logging instructions.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
For reserving a chunk of memory for kdump kernel, args need be
appended to kernel cmdline. For different Arch, different
bootloaders and related config files are used, it's a little
annoying. Using grubby, it can be very easy to append a single
arg to kernel cmdline, and can save words in howto document.
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: WANG Chao <chaowang@redhat.com>
Save vmcore-dmesg.txt before saving vmcore. For ssh targets, it assumes
that ssh is enabled. No scp logic as I don't have a local copy of
kernel log buffers and saving one will consume extra memory. We
can possibly enhance this logic to save kernel log buffers first locally
and then scp it (For setups which allow scp but disable ssh access).
(log is from Vivek Goyal <vgoyal@redhat.com>)
And add 1 section to describe it in kexec-kdump-howto.txt
v3->v4:
Remove old description of dmesg in kexec-kdump-howto.txt, now
add a new section to describe it, and note user kernel log
buffers won't be available if dump target is raw device.
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Firstly rename dump_rootfs to dump_to_rootfs to remove the ambiguity
about dump_rootfs. Then add it as one of default options. That means
user can specify dump_to_rootfs to be default action manually, then
it will take action when specified target dump failed.
Secondly, in rhel7 and fedora, when default action is not specified,
the default 'default' is dump_to_rootfs. Namely when specified target
dump failed, the kdump initrd will mount root and save kdump from
initramfs context. However in rhel6, the default 'default' is 'reboot'.
That means when specified target dump failed, the kdump initrd will
reboot systems. For being consistent with rhel6, change the default
'default' back to 'reboot'. And this can also keep logic simple, easier
to understand. Primarily, Our default dump target is root filesystem.
So keeping "default" as "dump_to_rootfs" and trying to dump to root
filesystem again when first attempt fails does not make much sense.
Meanwhile add the relevant description into kdump.conf,kdump.conf.5
and kexec-kdump-howto.txt.
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
We need fs dump target being mounted firstly before creating mkdumprd
This is because we want to get the mount options from kernel mountinfo
instead of simply mount it without considering mount options.
To avoid the filesystem being used by something other than kdump we
suggest them to mount it as 'ro', mkdumprd will remount it as 'rw' when
necessary and remount it back to 'ro'
In 2nd kernel kdump will still use 'rw' to mount it though.
Tested local read-only mounted fs dump.
[v1->v2]: improve documentation
add error handling for `mount -o remount,ro`
Fixed the changelog per Vivek's comment
The code was reviewed by Vivek.
Signed-off-by: Dave Young <dyoung@redhat.com>
For devices with filesystem, udev /dev/disk/by-uuid/* links are usually
reliable. But one exception is multipath devices, child and top layer
device may have same uuid.
As dm devices maintain /dev/mapper/* as persistent names, so converting to
/dev/mapper/* firstly then try by-uuid/* and by-id/*
Also because user know better what's the persistent name we just document well
to suggest user use persistent name in kdump.conf. it's suggested to
to use lvm or multipath canonical names or uuid/label.
Updated kdump.conf examples and related chunks in kexec-kdump-howto.txt
use lvm /dev/vg/<devname> in examples
Signed-off-by: Dave Young <dyoung@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Copy comments from the bz:
In rhel7 onwards, we will require dump target filesystem to be mounted in first kernel so that kdump can make use of same mount options instead of trying to come up with its own mount options. This should make mounting that file system safer. Also it reduces complexity in kdump code.
That will mean one needs to put an entry for the dump file system in /etc/fstab
so that after reboot when kdump service starts, it can find the dump target and build initramfs instead of failing.
Currently net options means either nfs or ssh dump.
Better to split these two into standalone options. That's more clear to user.
after the split, ssh dump need user specify "ssh user@host"
nfs dump need user specify "nfs host:nfsshare"
Signed-off-by: Dave Young <dyoung@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
We should use systemctl instead of service to start/restart the kdump service
update kexec-kdump-howto.txt as well.
Signed-off-by: Dave Young <dyoung@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
we now switched to systemd, 'service kdump propagate' does not work anymore.
update the alert message to use 'kdumpctl propagate'
vivek: update kexec-kdump-howto.txt as well.
Signed-off-by: Dave Young <dyoung@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Resolves: bz821997
dracut will mount rootfs for us, so we need not pass root to fstab again here.
Here remove the root-mount line.
This will depends on the root=cmdline is right, by default kdump will
inherit it from /proc/cmdline.
Vivek: add document about the assumption for the root= cmdline issue.
Signed-off-by: Dave Young <dyoung@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Original patch is from Amerigo, but it has changed a lot:
remove multi dump
refreshed with latest git for the dump instruction function restructure
fixed the behavior of do_kdump_pre, if kdump_pre fails it will reboot
update the docs
check the existance and executable of kdump_pre/post files,
also check the timestamp of them for rebuilding.
refresh patch,
Address comments from vivek:
s/hush/bash in docs
fix the copy-paste error in kdump post error message
s/reboot\/halt/reboot in kexec-kdump-howto.txt
Signed-off-by: Dave Young <dyoung@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
1. add core_collector filter support to ssh dump
2. scp can be specified in kdump.conf
3. error out if no '-F' with makedumpfile
4. add proper explanation and examples to kdump.conf[.5] and kexec-kdump-howto.txt.
v1->v2: add verify_core_collector function
v2->v3: optimize the code, remove local variable for default core_collector
Signed-off-by: Dave Young <dyoung@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Update core_collector in kdump.conf[.5]:
1. accept <command> not limited to makedumpfile
2. add notes about default core_collector
3. add notes about flattened vmcore
Signed-off-by: Dave Young <dyoung@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
kdump_post and kdump_pre are not implemented, remove them from kdump.conf[.5]
Signed-off-by: Dave Young <dyoung@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
