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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
commit | ace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch) | |
tree | b2d64bc10158fdd5497876388cd68142ca374ed3 /Documentation/ABI/testing/sysfs-firmware-memmap | |
parent | Initial commit. (diff) | |
download | linux-upstream/6.6.15.tar.xz linux-upstream/6.6.15.zip |
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'Documentation/ABI/testing/sysfs-firmware-memmap')
-rw-r--r-- | Documentation/ABI/testing/sysfs-firmware-memmap | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-firmware-memmap b/Documentation/ABI/testing/sysfs-firmware-memmap new file mode 100644 index 0000000000..9205122fa4 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-firmware-memmap @@ -0,0 +1,75 @@ +What: /sys/firmware/memmap/ +Date: June 2008 +Contact: Bernhard Walle <bernhard.walle@gmx.de> +Description: + On all platforms, the firmware provides a memory map which the + kernel reads. The resources from that memory map are registered + in the kernel resource tree and exposed to userspace via + /proc/iomem (together with other resources). + + However, on most architectures that firmware-provided memory + map is modified afterwards by the kernel itself, either because + the kernel merges that memory map with other information or + just because the user overwrites that memory map via command + line. + + kexec needs the raw firmware-provided memory map to setup the + parameter segment of the kernel that should be booted with + kexec. Also, the raw memory map is useful for debugging. For + that reason, /sys/firmware/memmap is an interface that provides + the raw memory map to userspace. + + The structure is as follows: Under /sys/firmware/memmap there + are subdirectories with the number of the entry as their name:: + + /sys/firmware/memmap/0 + /sys/firmware/memmap/1 + /sys/firmware/memmap/2 + /sys/firmware/memmap/3 + ... + + The maximum depends on the number of memory map entries provided + by the firmware. The order is just the order that the firmware + provides. + + Each directory contains three files: + + ======== ===================================================== + start The start address (as hexadecimal number with the + '0x' prefix). + end The end address, inclusive (regardless whether the + firmware provides inclusive or exclusive ranges). + type Type of the entry as string. See below for a list of + valid types. + ======== ===================================================== + + So, for example:: + + /sys/firmware/memmap/0/start + /sys/firmware/memmap/0/end + /sys/firmware/memmap/0/type + /sys/firmware/memmap/1/start + ... + + Currently following types exist: + + - System RAM + - ACPI Tables + - ACPI Non-volatile Storage + - Unusable memory + - Persistent Memory (legacy) + - Persistent Memory + - Soft Reserved + - reserved + + Following shell snippet can be used to display that memory + map in a human-readable format:: + + #!/bin/bash + cd /sys/firmware/memmap + for dir in * ; do + start=$(cat $dir/start) + end=$(cat $dir/end) + type=$(cat $dir/type) + printf "%016x-%016x (%s)\n" $start $[ $end +1] "$type" + done |