Used by tasks that are started early in the boot process, before reliable userspace logging support is running. Output is logged to the same place as kernel logging.


  • a - the length of the string to log in bytes. Maximum length is 4096 bytes.
  • b - a usermode pointer to the start of the UTF-8 encoded string.


  • 0 if the system call succeeded
  • 1 if the string was too long
  • 2 if the string was not valid UTF-8
  • 3 if the task making the syscall doesn't have the EarlyLogging capability

Capabilities needed

The EarlyLogging capability is needed to make this system call.