Re: [PATCH 1/1] kernel/crash_core.c - Add crashkernel=auto for x86 and ARM

Hi,

On 11/18/20 3:24 PM, Saeed Mirzamohammadi wrote:

This adds crashkernel=auto feature to configure reserved memory for vmcore creation to both x86 and ARM platforms based on the total memory size.

Cc: stable@vger.kernel.org

why?

Signed-off-by: John Donnelly john.p.donnelly@oracle.com Signed-off-by: Saeed Mirzamohammadi saeed.mirzamohammadi@oracle.com

---

Documentation/admin-guide/kdump/kdump.rst | 5 +++++ arch/arm64/Kconfig | 26 ++++++++++++++++++++++- arch/arm64/configs/defconfig | 1 + arch/x86/Kconfig | 26 ++++++++++++++++++++++- arch/x86/configs/x86_64_defconfig | 1 + kernel/crash_core.c | 20 +++++++++++++++-- 6 files changed, 75 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 1515f6f153a0..d359dcffa80e 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig

@@ -1135,6 +1135,30 @@ config CRASH_DUMP For more details see Documentation/admin-guide/kdump/kdump.rst +if CRASH_DUMP

+config CRASH_AUTO_STR

•    string "Memory reserved for crash kernel"
  

use tab instead of spaces above.

• depends on CRASH_DUMP

•    default "1G-64G:128M,64G-1T:256M,1T-:512M"
  

ditto.

• help

•  This configures the reserved memory dependent
  

•  on the value of System RAM. The syntax is:
  

•  crashkernel=<range1>:<size1>[,<range2>:<size2>,...][@offset]
  

•              range=start-[end]
  

•  For example:
  

•      crashkernel=512M-2G:64M,2G-:128M
  

•  This would mean:
  

•      1) if the RAM is smaller than 512M, then don't reserve anything
  

•         (this is the "rescue" case)
  

•      2) if the RAM size is between 512M and 2G (exclusive), then reserve 64M
  

•      3) if the RAM size is larger than 2G, then reserve 128M
  

+endif # CRASH_DUMP

config XEN_DOM0 def_bool y depends on XEN

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index f6946b81f74a..bacd17312bb1 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig

@@ -2049,6 +2049,30 @@ config CRASH_DUMP (CONFIG_RELOCATABLE=y). For more details see Documentation/admin-guide/kdump/kdump.rst +if CRASH_DUMP

+config CRASH_AUTO_STR

•    string "Memory reserved for crash kernel" if X86_64
  

ditto.

• depends on CRASH_DUMP

•    default "1G-64G:128M,64G-1T:256M,1T-:512M"
  

ditto.

• help

•  This configures the reserved memory dependent
  

•  on the value of System RAM. The syntax is:
  

•  crashkernel=<range1>:<size1>[,<range2>:<size2>,...][@offset]
  

•              range=start-[end]
  

•  For example:
  

•      crashkernel=512M-2G:64M,2G-:128M
  

•  This would mean:
  

•      1) if the RAM is smaller than 512M, then don't reserve anything
  

•         (this is the "rescue" case)
  

•      2) if the RAM size is between 512M and 2G (exclusive), then reserve 64M
  

•      3) if the RAM size is larger than 2G, then reserve 128M
  

+endif # CRASH_DUMP

config KEXEC_JUMP bool "kexec jump" depends on KEXEC && HIBERNATION

diff --git a/kernel/crash_core.c b/kernel/crash_core.c index 106e4500fd53..a44cd9cc12c4 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -7,6 +7,7 @@ #include <linux/crash_core.h> #include <linux/utsname.h> #include <linux/vmalloc.h> +#include <linux/kexec.h> #include <asm/page.h> #include <asm/sections.h> @@ -41,6 +42,15 @@ static int __init parse_crashkernel_mem(char *cmdline, unsigned long long *crash_base) { char *cur = cmdline, *tmp;

• unsigned long long total_mem = system_ram;
• /*

• * Firmware sometimes reserves some memory regions for it's own use.
  

its

• * so we get less than actual system memory size.
  

• * Workaround this by round up the total size to 128M which is
  

• * enough for most test cases.
  

• */
  

• total_mem = roundup(total_mem, SZ_128M);

thanks.