dell_rbu.rst

  1=========================================
  2Dell Remote BIOS Update driver (dell_rbu)
  3=========================================
  4
  5Purpose
  6=======
  7
  8Document demonstrating the use of the Dell Remote BIOS Update driver
  9for updating BIOS images on Dell servers and desktops.
 10
 11Scope
 12=====
 13
 14This document discusses the functionality of the rbu driver only.
 15It does not cover the support needed from applications to enable the BIOS to
 16update itself with the image downloaded in to the memory.
 17
 18Overview
 19========
 20
 21This driver works with Dell OpenManage or Dell Update Packages for updating
 22the BIOS on Dell servers (starting from servers sold since 1999), desktops
 23and notebooks (starting from those sold in 2005).
 24
 25Please go to  http://support.dell.com register and you can find info on
 26OpenManage and Dell Update packages (DUP).
 27
 28Libsmbios can also be used to update BIOS on Dell systems go to
 29https://linux.dell.com/libsmbios/ for details.
 30
 31Dell_RBU driver supports BIOS update using the monolithic image and packetized
 32image methods. In case of monolithic the driver allocates a contiguous chunk
 33of physical pages having the BIOS image. In case of packetized the app
 34using the driver breaks the image in to packets of fixed sizes and the driver
 35would place each packet in contiguous physical memory. The driver also
 36maintains a link list of packets for reading them back.
 37
 38If the dell_rbu driver is unloaded all the allocated memory is freed.
 39
 40The rbu driver needs to have an application (as mentioned above) which will
 41inform the BIOS to enable the update in the next system reboot.
 42
 43The user should not unload the rbu driver after downloading the BIOS image
 44or updating.
 45
 46The driver load creates the following directories under the /sys file system::
 47
 48	/sys/class/firmware/dell_rbu/loading
 49	/sys/class/firmware/dell_rbu/data
 50	/sys/devices/platform/dell_rbu/image_type
 51	/sys/devices/platform/dell_rbu/data
 52	/sys/devices/platform/dell_rbu/packet_size
 53
 54The driver supports two types of update mechanism; monolithic and packetized.
 55These update mechanism depends upon the BIOS currently running on the system.
 56Most of the Dell systems support a monolithic update where the BIOS image is
 57copied to a single contiguous block of physical memory.
 58
 59In case of packet mechanism the single memory can be broken in smaller chunks
 60of contiguous memory and the BIOS image is scattered in these packets.
 61
 62By default the driver uses monolithic memory for the update type. This can be
 63changed to packets during the driver load time by specifying the load
 64parameter image_type=packet.  This can also be changed later as below::
 65
 66	echo packet > /sys/devices/platform/dell_rbu/image_type
 67
 68In packet update mode the packet size has to be given before any packets can
 69be downloaded. It is done as below::
 70
 71	echo XXXX > /sys/devices/platform/dell_rbu/packet_size
 72
 73In the packet update mechanism, the user needs to create a new file having
 74packets of data arranged back to back. It can be done as follows:
 75The user creates packets header, gets the chunk of the BIOS image and
 76places it next to the packetheader; now, the packetheader + BIOS image chunk
 77added together should match the specified packet_size. This makes one
 78packet, the user needs to create more such packets out of the entire BIOS
 79image file and then arrange all these packets back to back in to one single
 80file.
 81
 82This file is then copied to /sys/class/firmware/dell_rbu/data.
 83Once this file gets to the driver, the driver extracts packet_size data from
 84the file and spreads it across the physical memory in contiguous packet_sized
 85space.
 86
 87This method makes sure that all the packets get to the driver in a single operation.
 88
 89In monolithic update the user simply get the BIOS image (.hdr file) and copies
 90to the data file as is without any change to the BIOS image itself.
 91
 92Do the steps below to download the BIOS image.
 93
 941) echo 1 > /sys/class/firmware/dell_rbu/loading
 952) cp bios_image.hdr /sys/class/firmware/dell_rbu/data
 963) echo 0 > /sys/class/firmware/dell_rbu/loading
 97
 98The /sys/class/firmware/dell_rbu/ entries will remain till the following is
 99done.
100
101::
102
103	echo -1 > /sys/class/firmware/dell_rbu/loading
104
105Until this step is completed the driver cannot be unloaded.
106
107Also echoing either mono, packet or init in to image_type will free up the
108memory allocated by the driver.
109
110If a user by accident executes steps 1 and 3 above without executing step 2;
111it will make the /sys/class/firmware/dell_rbu/ entries disappear.
112
113The entries can be recreated by doing the following::
114
115	echo init > /sys/devices/platform/dell_rbu/image_type
116
117.. note:: echoing init in image_type does not change its original value.
118
119Also the driver provides /sys/devices/platform/dell_rbu/data readonly file to
120read back the image downloaded.
121
122.. note::
123
124   After updating the BIOS image a user mode application needs to execute
125   code which sends the BIOS update request to the BIOS. So on the next reboot
126   the BIOS knows about the new image downloaded and it updates itself.
127   Also don't unload the rbu driver if the image has to be updated.
128