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| author | Jiri Bohac <jbohac@suse.cz> | 2025-06-12 13:17:39 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-07-20 05:08:23 +0300 |
| commit | ce1bf19a34dfa1f418037cebe11f5d2c7adf9d1e (patch) | |
| tree | ff1a624b7bc1d93cc42b6f5a1d04014ab2b59742 | |
| parent | ab475510e0422bb5672d465f9d0f523d72fdb7f1 (diff) | |
| download | linux-ce1bf19a34dfa1f418037cebe11f5d2c7adf9d1e.tar.xz | |
kdump, documentation: describe craskernel CMA reservation
Describe the new crashkernel ",cma" suffix in Documentation/
Link: https://lkml.kernel.org/r/aEqpQwUy6gqSiUkV@dwarf.suse.cz
Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Donald Dutile <ddutile@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Philipp Rudo <prudo@redhat.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Tao Liu <ltao@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | Documentation/admin-guide/kdump/kdump.rst | 21 | ||||
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 22 |
2 files changed, 43 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst index 20fabdf6567e..9c6cd52f69cf 100644 --- a/Documentation/admin-guide/kdump/kdump.rst +++ b/Documentation/admin-guide/kdump/kdump.rst @@ -311,6 +311,27 @@ crashkernel syntax crashkernel=0,low +4) crashkernel=size,cma + + Reserve additional crash kernel memory from CMA. This reservation is + usable by the first system's userspace memory and kernel movable + allocations (memory balloon, zswap). Pages allocated from this memory + range will not be included in the vmcore so this should not be used if + dumping of userspace memory is intended and it has to be expected that + some movable kernel pages may be missing from the dump. + + A standard crashkernel reservation, as described above, is still needed + to hold the crash kernel and initrd. + + This option increases the risk of a kdump failure: DMA transfers + configured by the first kernel may end up corrupting the second + kernel's memory. + + This reservation method is intended for systems that can't afford to + sacrifice enough memory for standard crashkernel reservation and where + less reliable and possibly incomplete kdump is preferable to no kdump at + all. + Boot into System Kernel ----------------------- 1) Update the boot loader (such as grub, yaboot, or lilo) configuration diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index f1f2c0874da9..ac4a239b9388 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -986,6 +986,28 @@ 0: to disable low allocation. It will be ignored when crashkernel=X,high is not used or memory reserved is below 4G. + crashkernel=size[KMG],cma + [KNL, X86] Reserve additional crash kernel memory from + CMA. This reservation is usable by the first system's + userspace memory and kernel movable allocations (memory + balloon, zswap). Pages allocated from this memory range + will not be included in the vmcore so this should not + be used if dumping of userspace memory is intended and + it has to be expected that some movable kernel pages + may be missing from the dump. + + A standard crashkernel reservation, as described above, + is still needed to hold the crash kernel and initrd. + + This option increases the risk of a kdump failure: DMA + transfers configured by the first kernel may end up + corrupting the second kernel's memory. + + This reservation method is intended for systems that + can't afford to sacrifice enough memory for standard + crashkernel reservation and where less reliable and + possibly incomplete kdump is preferable to no kdump at + all. cryptomgr.notests [KNL] Disable crypto self-tests |