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    SubjectRe: [PATCH v3 1/1] kernel/crash_core: Add crashkernel=auto for vmcore creation
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    On 2/11/21 12:08 PM, Saeed Mirzamohammadi wrote:
    > This adds crashkernel=auto feature to configure reserved memory for
    > vmcore creation. CONFIG_CRASH_AUTO_STR is defined to be set for
    > different kernel distributions and different archs based on their
    > needs.
    >
    > Signed-off-by: Saeed Mirzamohammadi <saeed.mirzamohammadi@oracle.com>
    > Signed-off-by: John Donnelly <john.p.donnelly@oracle.com>
    > Tested-by: John Donnelly <john.p.donnelly@oracle.com>
    > ---
    > Documentation/admin-guide/kdump/kdump.rst | 3 ++-
    > .../admin-guide/kernel-parameters.txt | 6 +++++
    > arch/Kconfig | 24 +++++++++++++++++++
    > kernel/crash_core.c | 7 ++++++
    > 4 files changed, 39 insertions(+), 1 deletion(-)
    >
    > diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
    > index 2da65fef2a1c..e55cdc404c6b 100644
    > --- a/Documentation/admin-guide/kdump/kdump.rst
    > +++ b/Documentation/admin-guide/kdump/kdump.rst
    > @@ -285,7 +285,8 @@ This would mean:
    > 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
    >
    > -
    > +Or you can use crashkernel=auto to choose the crash kernel memory size
    > +based on the recommended configuration set for each arch.
    >
    > Boot into System Kernel
    > =======================
    > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
    > index 7d4e523646c3..aa2099465458 100644
    > --- a/Documentation/admin-guide/kernel-parameters.txt
    > +++ b/Documentation/admin-guide/kernel-parameters.txt
    > @@ -736,6 +736,12 @@
    > a memory unit (amount[KMG]). See also
    > Documentation/admin-guide/kdump/kdump.rst for an example.
    >
    > + crashkernel=auto
    > + [KNL] This parameter will set the reserved memory for
    > + the crash kernel based on the value of the CRASH_AUTO_STR
    > + that is the best effort estimation for each arch. See also
    > + arch/Kconfig for further details.
    > +
    > crashkernel=size[KMG],high
    > [KNL, X86-64] range could be above 4G. Allow kernel
    > to allocate physical memory region from top, so could
    > diff --git a/arch/Kconfig b/arch/Kconfig
    > index af14a567b493..f87c88ffa2f8 100644
    > --- a/arch/Kconfig
    > +++ b/arch/Kconfig
    > @@ -14,6 +14,30 @@ menu "General architecture-dependent options"
    > config CRASH_CORE
    > bool
    >
    > +if CRASH_CORE
    > +
    > +config CRASH_AUTO_STR
    > + string "Memory reserved for crash kernel"
    > + depends on CRASH_CORE
    > + default "1G-64G:128M,64G-1T:256M,1T-:512M"
    > + 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_CORE
    > +
    > config KEXEC_CORE
    > select CRASH_CORE
    > bool
    > diff --git a/kernel/crash_core.c b/kernel/crash_core.c
    > index 106e4500fd53..ab0a2b4b1ffa 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>
    > @@ -250,6 +251,12 @@ static int __init __parse_crashkernel(char *cmdline,
    > if (suffix)
    > return parse_crashkernel_suffix(ck_cmdline, crash_size,
    > suffix);
    > +#ifdef CONFIG_CRASH_AUTO_STR
    > + if (strncmp(ck_cmdline, "auto", 4) == 0) {
    > + ck_cmdline = CONFIG_CRASH_AUTO_STR;
    > + pr_info("Using crashkernel=auto, the size chosen is a best effort estimation.\n");
    > + }
    > +#endif
    > /*
    > * if the commandline contains a ':', then that's the extended
    > * syntax -- if not, it must be the classic syntax
    >


    Hello.

    Ping.

    Can we get this reviewed and staged ?

    Thank you.

    John.


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