1*4882a593SmuzhiyunWhat: /sys/kernel/boot_params 2*4882a593SmuzhiyunDate: December 2013 3*4882a593SmuzhiyunContact: Dave Young <dyoung@redhat.com> 4*4882a593SmuzhiyunDescription: The /sys/kernel/boot_params directory contains two 5*4882a593Smuzhiyun files: "data" and "version" and one subdirectory "setup_data". 6*4882a593Smuzhiyun It is used to export the kernel boot parameters of an x86 7*4882a593Smuzhiyun platform to userspace for kexec and debugging purpose. 8*4882a593Smuzhiyun 9*4882a593Smuzhiyun If there's no setup_data in boot_params the subdirectory will 10*4882a593Smuzhiyun not be created. 11*4882a593Smuzhiyun 12*4882a593Smuzhiyun "data" file is the binary representation of struct boot_params. 13*4882a593Smuzhiyun 14*4882a593Smuzhiyun "version" file is the string representation of boot 15*4882a593Smuzhiyun protocol version. 16*4882a593Smuzhiyun 17*4882a593Smuzhiyun "setup_data" subdirectory contains the setup_data data 18*4882a593Smuzhiyun structure in boot_params. setup_data is maintained in kernel 19*4882a593Smuzhiyun as a link list. In "setup_data" subdirectory there's one 20*4882a593Smuzhiyun subdirectory for each link list node named with the number 21*4882a593Smuzhiyun of the list nodes. The list node subdirectory contains two 22*4882a593Smuzhiyun files "type" and "data". "type" file is the string 23*4882a593Smuzhiyun representation of setup_data type. "data" file is the binary 24*4882a593Smuzhiyun representation of setup_data payload. 25*4882a593Smuzhiyun 26*4882a593Smuzhiyun The whole boot_params directory structure is like below:: 27*4882a593Smuzhiyun 28*4882a593Smuzhiyun /sys/kernel/boot_params 29*4882a593Smuzhiyun |__ data 30*4882a593Smuzhiyun |__ setup_data 31*4882a593Smuzhiyun | |__ 0 32*4882a593Smuzhiyun | | |__ data 33*4882a593Smuzhiyun | | |__ type 34*4882a593Smuzhiyun | |__ 1 35*4882a593Smuzhiyun | |__ data 36*4882a593Smuzhiyun | |__ type 37*4882a593Smuzhiyun |__ version 38*4882a593Smuzhiyun 39*4882a593SmuzhiyunUsers: Kexec 40