Motivation: ============= Previously, LKP reported a building error. When investigating, it can't be resolved reasonablly with the present messy kdump config items. https://lore.kernel.org/oe-kbuild-all/202312182200.Ka7MzifQ-lkp@xxxxxxxxx/ The kdump (crash dumping) related config items could causes confusions: Firstly, --- CRASH_CORE enables codes including - crashkernel reservation parsing; - elfcorehdr updating; - vmcoreinfo saving; - crash hotplug handling; Now fadump of powerpc, kcore dynamic debugging and kdump all selects CRASH_CORE, while fadump - fadump needs crashkernel parsing, vmcoreinfo and accessing global variable 'elfcorehdr_addr'; - kcore needs saved vmcoreinfo; - kdump needs all of the current kernel/crash_core.c. So only enabling PROC_CORE or FA_DUMP will enable CRASH_CORE will confuse people that we enable the core code of kdump. Actually it's not. Secondly, --- It's not reasonable to allow KEXEC_CORE select CRASH_CORE. Because KEXEC_CORE enables codes which allocate control pages, copy kexec/kdump segments, and prepare for switching. These codes are shared by both kexec_load and kexec_file_load, and by both kexec reboot and kdump. We could want kexec reboot, but disable kdump. In that case, CRASH_CORE should not be selected. Thirdly, --- It's not reasonable to allow CRASH_DUMP select KEXEC_CORE. That could make KEXEC_CORE, CRASH_DUMP are enabled independently from KEXEC or KEXEC_FILE. However, w/o KEXEC or KEXEC_FILE, the KEXEC_CORE code built in doesn't make any sense because no kernel loading or switching will happen to utilize the KEXEC_CORE code. Changes: =========== 1, split CRASH_CORE codes into three parts: 1. move the elfcorehdr upating code and crash hotplug handling code into kernel/kexec_core.c. Both KEXEC and KEXEC_FILE will use them. 2. split crashkernel reservation code out into kernel/crash_reserve.c, add CRASH_RESERVE to control its enabling; 3. rename the left kernel/crash_core.c to kernel/vmcore_info.c since only vmcoreinfo is saved in the file, and add VMCORE_INFO to control its enabling; 2, rename the current kernel/crash_dump.c to kernel/elfcorehdr.c because it only defines elfcorehdr_addr and function parse_elfcorehdr() in the file. And build it in when VMCORE_INFO is enabled. Achievement: =========== With above changes, I can rearrange the config items as below (the right item depends on or is selected by the left item): PROC_KCORE -----------> VMCORE_INFO |----------> VMCORE_INFO FA_DUMP----| |----------> CRASH_RESERVE ---->VMCORE_INFO / |---->CRASH_RESERVE KEXEC --| /| |--> KEXEC_CORE--> CRASH_DUMP-->/-|---->PROC_VMCORE KEXEC_FILE --| \ | \---->CRASH_HOTPLUG KEXEC --| |--> KEXEC_CORE (for kexec reboot only) KEXEC_FILE --| Baoquan He (5): kexec_core: move kdump related codes from crash_core.c to kexec_core.c kexec: split crashkernel reservation code out from crash_core.c crash: rename crash_core to vmcore_info crash: remove dependency of FA_DUMP on CRASH_DUMP crash: clean up CRASH_DUMP arch/arm64/Kconfig | 2 +- .../asm/{crash_core.h => crash_reserve.h} | 4 +- arch/arm64/kernel/Makefile | 2 +- .../kernel/{crash_core.c => vmcore_info.c} | 2 +- arch/powerpc/Kconfig | 4 +- arch/powerpc/kernel/setup-common.c | 2 +- arch/powerpc/mm/nohash/kaslr_booke.c | 4 +- arch/powerpc/platforms/powernv/opal-core.c | 2 +- arch/riscv/Kconfig | 2 +- .../asm/{crash_core.h => crash_reserve.h} | 4 +- arch/riscv/kernel/Makefile | 2 +- .../kernel/{crash_core.c => vmcore_info.c} | 2 +- arch/x86/Kconfig | 2 +- .../asm/{crash_core.h => crash_reserve.h} | 6 +- arch/x86/kernel/Makefile | 2 +- .../{crash_core_32.c => vmcore_info_32.c} | 2 +- .../{crash_core_64.c => vmcore_info_64.c} | 2 +- drivers/firmware/qemu_fw_cfg.c | 14 +- fs/proc/Kconfig | 2 +- fs/proc/kcore.c | 2 +- include/linux/buildid.h | 2 +- include/linux/crash_reserve.h | 48 + include/linux/kexec.h | 27 +- include/linux/{crash_core.h => vmcore_info.h} | 78 +- kernel/Kconfig.kexec | 12 +- kernel/Makefile | 4 +- kernel/crash_core.c | 1065 ----------------- kernel/crash_reserve.c | 453 +++++++ kernel/{crash_dump.c => elfcorehdr.c} | 0 kernel/kexec_core.c | 408 +++++++ kernel/kexec_internal.h | 2 + kernel/ksysfs.c | 6 +- kernel/printk/printk.c | 4 +- kernel/vmcore_info.c | 233 ++++ lib/buildid.c | 2 +- 35 files changed, 1222 insertions(+), 1186 deletions(-) rename arch/arm64/include/asm/{crash_core.h => crash_reserve.h} (81%) rename arch/arm64/kernel/{crash_core.c => vmcore_info.c} (97%) rename arch/riscv/include/asm/{crash_core.h => crash_reserve.h} (78%) rename arch/riscv/kernel/{crash_core.c => vmcore_info.c} (96%) rename arch/x86/include/asm/{crash_core.h => crash_reserve.h} (92%) rename arch/x86/kernel/{crash_core_32.c => vmcore_info_32.c} (90%) rename arch/x86/kernel/{crash_core_64.c => vmcore_info_64.c} (94%) create mode 100644 include/linux/crash_reserve.h rename include/linux/{crash_core.h => vmcore_info.h} (59%) delete mode 100644 kernel/crash_core.c create mode 100644 kernel/crash_reserve.c rename kernel/{crash_dump.c => elfcorehdr.c} (100%) create mode 100644 kernel/vmcore_info.c -- 2.41.0
