On 02/09/22 at 02:56pm, Eric DeVolder wrote: > Support for CPU and memory hotplug for crash is controlled by the > CRASH_HOTPLUG configuration option, introduced by this patch. > > The CRASH_HOTPLUG_ELFCOREHDR_SZ related configuration option is > also introduced with this patch. > > Signed-off-by: Eric DeVolder <eric.devol...@oracle.com> > --- > arch/x86/Kconfig | 26 ++++++++++++++++++++++++++ > 1 file changed, 26 insertions(+) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index ebe8fc76949a..4e3374edab02 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -2060,6 +2060,32 @@ config CRASH_DUMP > (CONFIG_RELOCATABLE=y). > For more details see Documentation/admin-guide/kdump/kdump.rst > > +config CRASH_HOTPLUG > + bool "kernel updates of crash elfcorehdr" > + depends on CRASH_DUMP && (HOTPLUG_CPU || MEMORY_HOTPLUG) && KEXEC_FILE > + help > + Enable the kernel to update the crash elfcorehdr (which contains > + the list of CPUs and memory regions) directly when hot plug/unplug > + of CPUs or memory. Otherwise userspace must monitor these hot > + plug/unplug change notifications via udev in order to > + unload-then-reload the crash kernel so that the list of CPUs and > + memory regions is kept up-to-date. Note that the udev CPU and > + memory change notifications still occur (however, userspace is not > + required to monitor for crash dump purposes). > + > +config CRASH_HOTPLUG_ELFCOREHDR_SZ > + depends on CRASH_HOTPLUG > + int > + default 131072 > + help > + Specify the maximum size of the elfcorehdr buffer/segment. > + The 128KiB default is sized so that it can accommodate 2048 > + Elf64_Phdr, where each Phdr represents either a CPU or a > + region of memory. > + For example, this size can accommodate hotplugging a machine > + with up to 1024 CPUs and up to 1024 memory regions (e.g. 1TiB > + with 1024 1GiB memory DIMMs).
This example of memory could be a little misleading. The memory regions may not be related to memory DIMMs. System could split them into many smaller regions during bootup. Otherwise, this patch looks good to me. > + > config KEXEC_JUMP > bool "kexec jump" > depends on KEXEC && HIBERNATION > -- > 2.27.0 > _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec
