4.1 KiB
Name
sys - SerenityOS SysFS
Description
The kernel can expose system (kernel, firmware and hardware) related information in /sys.
bus directory
This directory include a subdirectory for each discovered and registered bus in the system.
Possible busses to be exposed in this directory are:
- The
pcisubdirectory that includes all discovered PCI devices as subdirectories. The subdirectories of the PCI devices include files with basic information on the devices. - The
usbsubdirectory that includes all discovered USB devices as files. The files of the USB devices export basic information on the devices.
dev directory
This directory include two subdirectories - block and char, each for block
and character devices respectively. The files in these subdirectories are not
device files, but merely a file with filename layout of "major:minor", to aid
userspace in generating the appropriate device files.
firmware directory
This directory include two subdirectories - acpi and bios.
The bios subdirectory maintains files of the exposed SMBIOS blobs, if present
by the firmware.
The acpi subdirectory maintains files of the exposed ACPI tables, if present
by the firmware.
A file called power_state is responsible for power state switching.
kernel directory
This directory includes two subdirectories - net and variables.
All other files in the directory are global data nodes which provide statistics
and other kernel-related data to userspace.
kernel directory entries
processes- This node exports a list of all processes that currently exist.cmdline- This node exports the kernel boot commandline that was passed from the bootloader.cpuinfo- This node exports information on the CPU.df- This node exports information on mounted filesystems and basic statistics on them.dmesg- This node exports information from the kernel log.interrupts- This node exports information on all IRQ handlers and basic statistics on them.load_base- This node reveals the loading address of the kernel.keymap- This node exports information on the currently used keymap.memstat- This node exports statistics on memory allocation in the kernel.profile- This node exports statistics on profiling data.stats- This node exports statistics on scheduler timing data.system_mode- This node exports the chosen system mode as it was decided based on the kernel commandline or a default value.uptime- This node exports the uptime data.power_state- This node only responds to write requests on it. A written value of1results in system reboot. A written value of2results in system shutdown.
net directory
adapters- This node exports information on all currently-discovered network adapters.arp- This node exports information on the kernel ARP table.local- This node exports information on local (Unix) sockets.tcp- This node exports information on TCP sockets.udp- This node exports information on UDP sockets.
variables directory
This subdirectory includes global settings of the kernel.
caps_lock_to_ctrl- This node controls remapping of of caps lock to the Ctrl key.kmalloc_stacks- This node controls whether to send information about kmalloc to debug log.ubsan_is_deadly- This node controls the deadliness of the kernel undefined behavior sanitizer errors.
Consistency and stability of data across multiple read operations
When opening a data node, the kernel generates the required data so it's prepared
for read operation when requested to. However, in order to ensure that multiple reads
will not create a corrupted data from that data node, a read operation alone will
not inquire the kernel to refresh the data.
To keep data output being refreshed, the userland has to re-open the data node with a
new file descriptor, or to perform the lseek syscall on the open file descriptor to
reset the the offset to 0.