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charset="utf-8" Several kexec and kdump sysfs entries are currently placed directly under /sys/kernel/, which clutters the directory and makes it harder to identify unrelated entries. To improve organization and readability, these entries are now moved under a dedicated directory, /sys/kernel/kexec. The following sysfs moved under new kexec sysfs node +------------------------------------+------------------+ | Old sysfs name | New sysfs name | | (under /sys/kernel) | (under /sys/kernel/kexec) | +---------------------------+---------------------------+ | kexec_loaded | loaded | +---------------------------+---------------------------+ | kexec_crash_loaded | crash_loaded | +---------------------------+---------------------------+ | kexec_crash_size | crash_size | +---------------------------+---------------------------+ | crash_elfcorehdr_size | crash_elfcorehdr_size | +---------------------------+---------------------------+ | kexec_crash_cma_ranges | crash_cma_ranges | +---------------------------+---------------------------+ For backward compatibility, symlinks are created at the old locations so that existing tools and scripts continue to work. These symlinks can be removed in the future once users have switched to the new path. While creating symlinks, entries are added in /sys/kernel/ that point to their new locations under /sys/kernel/kexec/. If an error occurs while adding a symlink, it is logged but does not stop initialization of the remaining kexec sysfs symlinks. The /sys/kernel/ entry is now controlled by CONFIG_CRASH_DUMP instead of CONFIG_VMCORE_INFO, as CONFIG_CRASH_DUMP also enables CONFIG_VMCORE_INFO. Cc: Aditya Gupta Cc: Andrew Morton Cc: Baoquan he Cc: Dave Young Cc: Hari Bathini Cc: Jiri Bohac Cc: Madhavan Srinivasan Cc: Mahesh J Salgaonkar Cc: Pingfan Liu Cc: Ritesh Harjani (IBM) Cc: Shivang Upadhyay Cc: Vivek Goyal Cc: linuxppc-dev@lists.ozlabs.org Cc: kexec@lists.infradead.org Signed-off-by: Sourabh Jain Acked-by: Baoquan He --- kernel/kexec_core.c | 141 ++++++++++++++++++++++++++++++++++++++++++++ kernel/ksysfs.c | 89 +--------------------------- 2 files changed, 142 insertions(+), 88 deletions(-) diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index fa00b239c5d9..02429499fb64 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -41,6 +41,7 @@ #include #include #include +#include =20 #include #include @@ -1229,3 +1230,143 @@ int kernel_kexec(void) kexec_unlock(); return error; } + +static ssize_t loaded_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%d\n", !!kexec_image); +} +static struct kobj_attribute loaded_attr =3D __ATTR_RO(loaded); + +#ifdef CONFIG_CRASH_DUMP +static ssize_t crash_loaded_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%d\n", kexec_crash_loaded()); +} +static struct kobj_attribute crash_loaded_attr =3D __ATTR_RO(crash_loaded); + +#ifdef CONFIG_CRASH_RESERVE +static ssize_t crash_cma_ranges_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + + ssize_t len =3D 0; + int i; + + for (i =3D 0; i < crashk_cma_cnt; ++i) { + len +=3D sysfs_emit_at(buf, len, "%08llx-%08llx\n", + crashk_cma_ranges[i].start, + crashk_cma_ranges[i].end); + } + return len; +} +static struct kobj_attribute crash_cma_ranges_attr =3D __ATTR_RO(crash_cma= _ranges); +#endif + +static ssize_t crash_size_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + ssize_t size =3D crash_get_memory_size(); + + if (size < 0) + return size; + + return sysfs_emit(buf, "%zd\n", size); +} +static ssize_t crash_size_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + unsigned long cnt; + int ret; + + if (kstrtoul(buf, 0, &cnt)) + return -EINVAL; + + ret =3D crash_shrink_memory(cnt); + return ret < 0 ? ret : count; +} +static struct kobj_attribute crash_size_attr =3D __ATTR_RW(crash_size); + +#ifdef CONFIG_CRASH_HOTPLUG +static ssize_t crash_elfcorehdr_size_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + unsigned int sz =3D crash_get_elfcorehdr_size(); + + return sysfs_emit(buf, "%u\n", sz); +} +static struct kobj_attribute crash_elfcorehdr_size_attr =3D __ATTR_RO(cras= h_elfcorehdr_size); + +#endif /* CONFIG_CRASH_HOTPLUG */ +#endif /* CONFIG_CRASH_DUMP */ + +static struct attribute *kexec_attrs[] =3D { + &loaded_attr.attr, +#ifdef CONFIG_CRASH_DUMP + &crash_loaded_attr.attr, + &crash_size_attr.attr, +#ifdef CONFIG_CRASH_RESERVE + &crash_cma_ranges_attr.attr, +#endif +#ifdef CONFIG_CRASH_HOTPLUG + &crash_elfcorehdr_size_attr.attr, +#endif +#endif + NULL +}; + +struct kexec_link_entry { + const char *target; + const char *name; +}; + +static struct kexec_link_entry kexec_links[] =3D { + { "loaded", "kexec_loaded" }, +#ifdef CONFIG_CRASH_DUMP + { "crash_loaded", "kexec_crash_loaded" }, + { "crash_size", "kexec_crash_size" }, +#ifdef CONFIG_CRASH_RESERVE + {"crash_cma_ranges", "kexec_crash_cma_ranges"}, +#endif +#ifdef CONFIG_CRASH_HOTPLUG + { "crash_elfcorehdr_size", "crash_elfcorehdr_size" }, +#endif +#endif +}; + +static struct kobject *kexec_kobj; +ATTRIBUTE_GROUPS(kexec); + +static int __init init_kexec_sysctl(void) +{ + int error; + int i; + + kexec_kobj =3D kobject_create_and_add("kexec", kernel_kobj); + if (!kexec_kobj) { + pr_err("failed to create kexec kobject\n"); + return -ENOMEM; + } + + error =3D sysfs_create_groups(kexec_kobj, kexec_groups); + if (error) + goto kset_exit; + + for (i =3D 0; i < ARRAY_SIZE(kexec_links); i++) { + error =3D compat_only_sysfs_link_entry_to_kobj(kernel_kobj, kexec_kobj, + kexec_links[i].target, + kexec_links[i].name); + if (error) + pr_err("Unable to create %s symlink (%d)", kexec_links[i].name, error); + } + + return 0; + +kset_exit: + kobject_put(kexec_kobj); + return error; +} + +subsys_initcall(init_kexec_sysctl); diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c index 0ff2179bc603..a9e6354d9e25 100644 --- a/kernel/ksysfs.c +++ b/kernel/ksysfs.c @@ -12,7 +12,7 @@ #include #include #include -#include +#include #include #include #include @@ -119,68 +119,6 @@ static ssize_t profiling_store(struct kobject *kobj, KERNEL_ATTR_RW(profiling); #endif =20 -#ifdef CONFIG_KEXEC_CORE -static ssize_t kexec_loaded_show(struct kobject *kobj, - struct kobj_attribute *attr, char *buf) -{ - return sysfs_emit(buf, "%d\n", !!kexec_image); -} -KERNEL_ATTR_RO(kexec_loaded); - -#ifdef CONFIG_CRASH_DUMP -static ssize_t kexec_crash_loaded_show(struct kobject *kobj, - struct kobj_attribute *attr, char *buf) -{ - return sysfs_emit(buf, "%d\n", kexec_crash_loaded()); -} -KERNEL_ATTR_RO(kexec_crash_loaded); - -#ifdef CONFIG_CRASH_RESERVE -static ssize_t kexec_crash_cma_ranges_show(struct kobject *kobj, - struct kobj_attribute *attr, char *buf) -{ - - ssize_t len =3D 0; - int i; - - for (i =3D 0; i < crashk_cma_cnt; ++i) { - len +=3D sysfs_emit_at(buf, len, "%08llx-%08llx\n", - crashk_cma_ranges[i].start, - crashk_cma_ranges[i].end); - } - return len; -} -KERNEL_ATTR_RO(kexec_crash_cma_ranges); -#endif /* CONFIG_CRASH_RESERVE */ - -static ssize_t kexec_crash_size_show(struct kobject *kobj, - struct kobj_attribute *attr, char *buf) -{ - ssize_t size =3D crash_get_memory_size(); - - if (size < 0) - return size; - - return sysfs_emit(buf, "%zd\n", size); -} -static ssize_t kexec_crash_size_store(struct kobject *kobj, - struct kobj_attribute *attr, - const char *buf, size_t count) -{ - unsigned long cnt; - int ret; - - if (kstrtoul(buf, 0, &cnt)) - return -EINVAL; - - ret =3D crash_shrink_memory(cnt); - return ret < 0 ? ret : count; -} -KERNEL_ATTR_RW(kexec_crash_size); - -#endif /* CONFIG_CRASH_DUMP*/ -#endif /* CONFIG_KEXEC_CORE */ - #ifdef CONFIG_VMCORE_INFO =20 static ssize_t vmcoreinfo_show(struct kobject *kobj, @@ -192,18 +130,6 @@ static ssize_t vmcoreinfo_show(struct kobject *kobj, } KERNEL_ATTR_RO(vmcoreinfo); =20 -#ifdef CONFIG_CRASH_HOTPLUG -static ssize_t crash_elfcorehdr_size_show(struct kobject *kobj, - struct kobj_attribute *attr, char *buf) -{ - unsigned int sz =3D crash_get_elfcorehdr_size(); - - return sysfs_emit(buf, "%u\n", sz); -} -KERNEL_ATTR_RO(crash_elfcorehdr_size); - -#endif - #endif /* CONFIG_VMCORE_INFO */ =20 /* whether file capabilities are enabled */ @@ -273,21 +199,8 @@ static struct attribute * kernel_attrs[] =3D { #ifdef CONFIG_PROFILING &profiling_attr.attr, #endif -#ifdef CONFIG_KEXEC_CORE - &kexec_loaded_attr.attr, -#ifdef CONFIG_CRASH_DUMP - &kexec_crash_loaded_attr.attr, - &kexec_crash_size_attr.attr, -#ifdef CONFIG_CRASH_RESERVE - &kexec_crash_cma_ranges_attr.attr, -#endif -#endif -#endif #ifdef CONFIG_VMCORE_INFO &vmcoreinfo_attr.attr, -#ifdef CONFIG_CRASH_HOTPLUG - &crash_elfcorehdr_size_attr.attr, -#endif #endif #ifndef CONFIG_TINY_RCU &rcu_expedited_attr.attr, --=20 2.51.1 From nobody Tue Dec 2 02:43:46 2025 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DD54E350A25 for ; 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charset="utf-8" The previous commit ("kexec: move sysfs entries to /sys/kernel/kexec") moved all existing kexec sysfs entries to a new location. The ABI document is updated to include a note about the deprecation of the old kexec sysfs entries. The following kexec sysfs entries are deprecated: - /sys/kernel/kexec_loaded - /sys/kernel/kexec_crash_loaded - /sys/kernel/kexec_crash_size - /sys/kernel/crash_elfcorehdr_size - /sys/kernel/kexec_crash_cma_ranges Cc: Aditya Gupta Cc: Andrew Morton Cc: Baoquan he Cc: Dave Young Cc: Hari Bathini Cc: Jiri Bohac Cc: Madhavan Srinivasan Cc: Mahesh J Salgaonkar Cc: Pingfan Liu Cc: Ritesh Harjani (IBM) Cc: Shivang Upadhyay Cc: Vivek Goyal Cc: linuxppc-dev@lists.ozlabs.org Cc: kexec@lists.infradead.org Signed-off-by: Sourabh Jain Acked-by: Baoquan He --- .../sysfs-kernel-kexec-kdump | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) rename Documentation/ABI/{testing =3D> obsolete}/sysfs-kernel-kexec-kdump = (63%) diff --git a/Documentation/ABI/testing/sysfs-kernel-kexec-kdump b/Documenta= tion/ABI/obsolete/sysfs-kernel-kexec-kdump similarity index 63% rename from Documentation/ABI/testing/sysfs-kernel-kexec-kdump rename to Documentation/ABI/obsolete/sysfs-kernel-kexec-kdump index f6089e38de5f..ba26a6a1d2be 100644 --- a/Documentation/ABI/testing/sysfs-kernel-kexec-kdump +++ b/Documentation/ABI/obsolete/sysfs-kernel-kexec-kdump @@ -1,3 +1,21 @@ +NOTE: all the ABIs listed in this file are deprecated and will be removed = after 2028. + +Here are the alternative ABIs: ++------------------------------------+------------------------------------= -----+ +| Deprecated | Alternative = | ++------------------------------------+------------------------------------= -----+ +| /sys/kernel/kexec_loaded | /sys/kernel/kexec/loaded = | ++------------------------------------+------------------------------------= -----+ +| /sys/kernel/kexec_crash_loaded | /sys/kernel/kexec/crash_loaded = | ++------------------------------------+------------------------------------= -----+ +| /sys/kernel/kexec_crash_size | /sys/kernel/kexec/crash_size = | ++------------------------------------+------------------------------------= -----+ +| /sys/kernel/crash_elfcorehdr_size | /sys/kernel/kexec/crash_elfcorehdr_= size | ++------------------------------------+------------------------------------= -----+ +| /sys/kernel/kexec_crash_cma_ranges | /sys/kernel/kexec/crash_cma_ranges = | ++------------------------------------+------------------------------------= -----+ + + What: /sys/kernel/kexec_loaded Date: Jun 2006 Contact: kexec@lists.infradead.org --=20 2.51.1 From nobody Tue Dec 2 02:43:46 2025 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4FFCA20B7ED for ; 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charset="utf-8" Add an ABI document for following kexec and kdump sysfs interface: - /sys/kernel/kexec/loaded - /sys/kernel/kexec/crash_loaded - /sys/kernel/kexec/crash_size - /sys/kernel/kexec/crash_elfcorehdr_size - /sys/kernel/kexec/crash_cma_ranges Cc: Aditya Gupta Cc: Andrew Morton Cc: Baoquan he Cc: Dave Young Cc: Hari Bathini Cc: Jiri Bohac Cc: Madhavan Srinivasan Cc: Mahesh J Salgaonkar Cc: Pingfan Liu Cc: Ritesh Harjani (IBM) Cc: Shivang Upadhyay Cc: Vivek Goyal Cc: linuxppc-dev@lists.ozlabs.org Cc: kexec@lists.infradead.org Signed-off-by: Sourabh Jain Acked-by: Baoquan He --- .../ABI/testing/sysfs-kernel-kexec-kdump | 61 +++++++++++++++++++ 1 file changed, 61 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-kernel-kexec-kdump diff --git a/Documentation/ABI/testing/sysfs-kernel-kexec-kdump b/Documenta= tion/ABI/testing/sysfs-kernel-kexec-kdump new file mode 100644 index 000000000000..f59051b5d96d --- /dev/null +++ b/Documentation/ABI/testing/sysfs-kernel-kexec-kdump @@ -0,0 +1,61 @@ +What: /sys/kernel/kexec/* +Date: Nov 2025 +Contact: kexec@lists.infradead.org +Description: + The /sys/kernel/kexec/* directory contains sysfs files + that provide information about the configuration status + of kexec and kdump. + +What: /sys/kernel/kexec/loaded +Date: Nov 2025 +Contact: kexec@lists.infradead.org +Description: read only + Indicates whether a new kernel image has been loaded + into memory using the kexec system call. It shows 1 if + a kexec image is present and ready to boot, or 0 if none + is loaded. +User: kexec tools, kdump service + +What: /sys/kernel/kexec/crash_loaded +Date: Nov 2025 +Contact: kexec@lists.infradead.org +Description: read only + Indicates whether a crash (kdump) kernel is currently + loaded into memory. It shows 1 if a crash kernel has been + successfully loaded for panic handling, or 0 if no crash + kernel is present. +User: Kexec tools, Kdump service + +What: /sys/kernel/kexec/crash_size +Date: Nov 2025 +Contact: kexec@lists.infradead.org +Description: read/write + Shows the amount of memory reserved for loading the crash + (kdump) kernel. It reports the size, in bytes, of the + crash kernel area defined by the crashkernel=3D parameter. + This interface also allows reducing the crashkernel + reservation by writing a smaller value, and the reclaimed + space is added back to the system RAM. +User: Kdump service + +What: /sys/kernel/kexec/crash_elfcorehdr_size +Date: Nov 2025 +Contact: kexec@lists.infradead.org +Description: read only + Indicates the preferred size of the memory buffer for the + ELF core header used by the crash (kdump) kernel. It defines + how much space is needed to hold metadata about the crashed + system, including CPU and memory information. This information + is used by the user space utility kexec to support updating the + in-kernel kdump image during hotplug operations. +User: Kexec tools + +What: /sys/kernel/kexec/crash_cma_ranges +Date: Nov 2025 +Contact: kexec@lists.infradead.org +Description: read only + Provides information about the memory ranges reserved from + the Contiguous Memory Allocator (CMA) area that are allocated + to the crash (kdump) kernel. It lists the start and end physical + addresses of CMA regions assigned for crashkernel use. +User: kdump service --=20 2.51.1