How has the crashkernel=auto parameter changed between RHEL8 minor releases?
Environment
- Red Hat Enterprise Linux (RHEL) 8
- kdump/kexec
crashkernel=autoparameter
Issue
- How has the
crashkernel=autoparameter changed between RHEL8 minor releases?
Resolution
RHEL8.0 and RHEL8.1
The amount of memory reserved for the kdump kernel can be estimated with the following scheme:
| architecture | system memory:memory reserved by crashkernel |
|---|---|
| x86_64 | 1G-64G:160M,64G-1T:256M,1T-:512M |
| s390x | 4G-64G:160M,64G-1T:256M,1T-:512M |
| arm64 | 2G-:512M |
| ppc64 | 2G-4G:384M,4G-16G:512M,16G-64G:1G,64G-128G:2G,128G-:4G |
RHEL8.2
bz1780432 was implemented in RHEL8.2, changing s390x allocations. The amount of memory reserved for the kdump kernel can be estimated with the following scheme:
| architecture | system memory:memory reserved by crashkernel |
|---|---|
| x86_64 | 1G-64G:160M,64G-1T:256M,1T-:512M |
| s390x | 1G-64G:160M,64G-1T:256M,1T-:512M |
| arm64 | 2G-:512M |
| ppc64 | 2G-4G:384M,4G-16G:512M,16G-64G:1G,64G-128G:2G,128G-:4G |
RHEL8.3
With bz1746644, This content is not included.this patch changed the crashkernel allocations. The amount of memory reserved for the kdump kernel can be estimated with the following scheme:
| architecture | system memory:memory reserved by crashkernel |
|---|---|
| x86_64 | 1G-4G:160M,4G-64G:192M,64G-1T:256M,1T-:512M |
| s390x | 1G-4G:160M,4G-64G:192M,64G-1T:256M,1T-:512M |
| arm64 | 2G-:512M |
| ppc64 | 2G-4G:384M,4G-16G:512M,16G-64G:1G,64G-128G:2G,128G-:4G |
RHEL8.8 or later
With bz2122874 was implemented in RHEL8.8 to increase reserved memory as RHEL9.
| architecture | system memory:memory reserved by crashkernel |
|---|---|
| x86_64 | 1G-4G:192M,4G-64G:256M,64G-:512M |
| s390x | 1G-4G:192M,4G-64G:256M,64G-:512M |
| arm64 | 2G-:512M |
| ppc64 | 2G-4G:384M,4G-16G:512M,16G-64G:1G,64G-128G:2G,128G-:4G |
Root Cause
Kbase How should the crashkernel parameter be configured for using kdump on Red Hat Enterprise Linux 8? refers to the latest RHEL8 codebase. That codebase has seen changes since previous RHEL8 minor versions.
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