linux/Documentation
Sourabh Jain aa0145563c crash: export crashkernel CMA reservation to userspace
Add a sysfs entry /sys/kernel/kexec_crash_cma_ranges to expose all CMA
crashkernel ranges.

This allows userspace tools configuring kdump to determine how much memory
is reserved for crashkernel.  If CMA is used, tools can warn users when
attempting to capture user pages with CMA reservation.

The new sysfs hold the CMA ranges in below format:

cat /sys/kernel/kexec_crash_cma_ranges
100000000-10c7fffff

The reason for not including Crash CMA Ranges in /proc/iomem is to avoid
conflicts.  It has been observed that contiguous memory ranges are
sometimes shown as two separate System RAM entries in /proc/iomem.  If a
CMA range overlaps two System RAM ranges, adding crashk_res to /proc/iomem
can create a conflict.  Reference [1] describes one such instance on the
PowerPC architecture.

Link: https://lkml.kernel.org/r/20251118071023.1673329-1-sourabhjain@linux.ibm.com
Link: https://lore.kernel.org/all/20251016142831.144515-1-sourabhjain@linux.ibm.com/ [1]
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Aditya Gupta <adityag@linux.ibm.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mahesh J Salgaonkar <mahesh@linux.ibm.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Cc: Shivang Upadhyay <shivangu@linux.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-11-20 14:03:44 -08:00
..
ABI crash: export crashkernel CMA reservation to userspace 2025-11-20 14:03:44 -08:00
accel
accounting
admin-guide sys_info: add a default kernel sys_info mask 2025-11-20 14:03:43 -08:00
arch - Make TDX and kexec work together 2025-10-04 10:01:30 -07:00
block
bpf bpf: disable and remove registers chain based liveness 2025-09-19 09:27:23 -07:00
cdrom
core-api dma-mapping updates for Linux 6.18: 2025-10-03 17:41:12 -07:00
cpu-freq cpufreq: Drop unused symbol CPUFREQ_ETERNAL 2025-10-01 13:57:22 +02:00
crypto crypto: doc - Add explicit title heading to API docs 2025-09-28 11:54:48 +08:00
dev-tools checkpatch: document new check PLACEHOLDER_USE 2025-11-11 16:48:29 -08:00
devicetree dt-bindings: gpio: ti,twl4030: Correct the schema $id path 2025-11-03 11:48:30 +01:00
doc-guide
driver-api pci-v6.18-changes 2025-10-06 10:41:03 -07:00
edac
fault-injection
fb fbdev fixes & enhancements for 6.18-rc1: 2025-10-10 09:36:23 -07:00
features OpenRISC updates for 6.18 2025-10-05 10:02:54 -07:00
filesystems Ext4 bug fixes for 6.18-rc2, including 2025-10-15 07:51:57 -07:00
firmware_class
firmware-guide Documentation: ACPI: i2c-muxes: fix I2C device references 2025-11-03 17:01:05 +01:00
fpga
gpu drm next for 6.18-rc1 2025-10-02 12:47:25 -07:00
hid
hwmon hwmon: (cros_ec) register fans into thermal framework cooling devices 2025-09-25 08:08:14 -07:00
i2c i2c: i801: Add support for Intel Wildcat Lake-U 2025-09-28 00:45:53 +02:00
iio
images
infiniband
input Input: add INPUT_PROP_HAPTIC_TOUCHPAD 2025-09-15 14:32:54 +02:00
isdn
kbuild Kbuild updates for 6.18 2025-10-01 20:58:51 -07:00
kernel-hacking
leds
litmus-tests
livepatch
locking
maintainer docs: maintainer: Fix ambiguous subheading formatting 2025-09-18 10:26:45 -06:00
mhi
misc-devices
mm Only two patch series in this pull request: 2025-10-05 12:11:07 -07:00
netlabel
netlink dpll: spec: add missing module-name and clock-id to pin-get reply 2025-10-27 18:20:36 -07:00
networking Documentation: netconsole: Remove obsolete contact people 2025-10-29 17:40:19 -07:00
nvdimm
nvme
PCI pci-v6.18-changes 2025-10-06 10:41:03 -07:00
pcmcia
peci
power It has been a relatively busy cycle in docsland, with changes all over: 2025-10-03 17:16:13 -07:00
process It has been a relatively busy cycle in docsland, with changes all over: 2025-10-03 17:16:13 -07:00
RCU RCU pull request for v6.18 2025-10-04 11:28:45 -07:00
rust docs: rust: add section on imports formatting 2025-10-17 00:56:20 +02:00
scheduler
scsi
security
sound ALSA: emu10k1: Fix typo in docs 2025-10-04 15:47:24 +02:00
sphinx docs: remove cdomain.py 2025-09-21 16:35:57 -06:00
sphinx-static
spi
staging It has been a relatively busy cycle in docsland, with changes all over: 2025-10-03 17:16:13 -07:00
sunrpc/xdr
target
tee Documentation: tee: Add Qualcomm TEE driver 2025-09-15 17:34:06 +02:00
timers
tools tools/rtla: Add remaining support for osnoise actions 2025-09-27 04:53:48 -04:00
trace Documentation: trace: histogram: Convert ftrace docs cross-reference 2025-09-18 11:49:26 -06:00
translations More power management updates for 6.18-rc1 2025-10-07 09:39:51 -07:00
usb
userspace-api It has been a relatively busy cycle in docsland, with changes all over: 2025-10-03 17:16:13 -07:00
virt KVM x86 fixes for 6.18: 2025-10-18 10:25:43 +02:00
w1 docs: w1: ds2482: fix typo in buses 2025-09-16 10:00:57 -06:00
watchdog
wmi
.gitignore
.renames.txt
atomic_bitops.txt
atomic_t.txt
Changes
CodingStyle
conf.py
docutils.conf
index.rst
Kconfig
Makefile
memory-barriers.txt
SubmittingPatches
subsystem-apis.rst