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0001 Purpose:
0002 Demonstrate the usage of the new open sourced rbu (Remote BIOS Update) driver
0003 for updating BIOS images on Dell servers and desktops.
0004 
0005 Scope:
0006 This document discusses the functionality of the rbu driver only.
0007 It does not cover the support needed from applications to enable the BIOS to
0008 update itself with the image downloaded in to the memory.
0009 
0010 Overview:
0011 This driver works with Dell OpenManage or Dell Update Packages for updating
0012 the BIOS on Dell servers (starting from servers sold since 1999), desktops
0013 and notebooks (starting from those sold in 2005).
0014 Please go to  http://support.dell.com register and you can find info on
0015 OpenManage and Dell Update packages (DUP).
0016 Libsmbios can also be used to update BIOS on Dell systems go to
0017 http://linux.dell.com/libsmbios/ for details.
0018 
0019 Dell_RBU driver supports BIOS update using the monolithic image and packetized
0020 image methods. In case of monolithic the driver allocates a contiguous chunk
0021 of physical pages having the BIOS image. In case of packetized the app
0022 using the driver breaks the image in to packets of fixed sizes and the driver
0023 would place each packet in contiguous physical memory. The driver also
0024 maintains a link list of packets for reading them back.
0025 If the dell_rbu driver is unloaded all the allocated memory is freed.
0026 
0027 The rbu driver needs to have an application (as mentioned above)which will
0028 inform the BIOS to enable the update in the next system reboot.
0029 
0030 The user should not unload the rbu driver after downloading the BIOS image
0031 or updating.
0032 
0033 The driver load creates the following directories under the /sys file system.
0034 /sys/class/firmware/dell_rbu/loading
0035 /sys/class/firmware/dell_rbu/data
0036 /sys/devices/platform/dell_rbu/image_type
0037 /sys/devices/platform/dell_rbu/data
0038 /sys/devices/platform/dell_rbu/packet_size
0039 
0040 The driver supports two types of update mechanism; monolithic and packetized.
0041 These update mechanism depends upon the BIOS currently running on the system.
0042 Most of the Dell systems support a monolithic update where the BIOS image is
0043 copied to a single contiguous block of physical memory.
0044 In case of packet mechanism the single memory can be broken in smaller chunks
0045 of contiguous memory and the BIOS image is scattered in these packets.
0046 
0047 By default the driver uses monolithic memory for the update type. This can be
0048 changed to packets during the driver load time by specifying the load
0049 parameter image_type=packet.  This can also be changed later as below
0050 echo packet > /sys/devices/platform/dell_rbu/image_type
0051 
0052 In packet update mode the packet size has to be given before any packets can
0053 be downloaded. It is done as below
0054 echo XXXX > /sys/devices/platform/dell_rbu/packet_size
0055 In the packet update mechanism, the user needs to create a new file having
0056 packets of data arranged back to back. It can be done as follows
0057 The user creates packets header, gets the chunk of the BIOS image and
0058 places it next to the packetheader; now, the packetheader + BIOS image chunk
0059 added together should match the specified packet_size. This makes one
0060 packet, the user needs to create more such packets out of the entire BIOS
0061 image file and then arrange all these packets back to back in to one single
0062 file.
0063 This file is then copied to /sys/class/firmware/dell_rbu/data.
0064 Once this file gets to the driver, the driver extracts packet_size data from
0065 the file and spreads it across the physical memory in contiguous packet_sized
0066 space.
0067 This method makes sure that all the packets get to the driver in a single operation.
0068 
0069 In monolithic update the user simply get the BIOS image (.hdr file) and copies
0070 to the data file as is without any change to the BIOS image itself.
0071 
0072 Do the steps below to download the BIOS image.
0073 1) echo 1 > /sys/class/firmware/dell_rbu/loading
0074 2) cp bios_image.hdr /sys/class/firmware/dell_rbu/data
0075 3) echo 0 > /sys/class/firmware/dell_rbu/loading
0076 
0077 The /sys/class/firmware/dell_rbu/ entries will remain till the following is
0078 done.
0079 echo -1 > /sys/class/firmware/dell_rbu/loading
0080 Until this step is completed the driver cannot be unloaded.
0081 Also echoing either mono, packet or init in to image_type will free up the
0082 memory allocated by the driver.
0083 
0084 If a user by accident executes steps 1 and 3 above without executing step 2;
0085 it will make the /sys/class/firmware/dell_rbu/ entries disappear.
0086 The entries can be recreated by doing the following
0087 echo init > /sys/devices/platform/dell_rbu/image_type
0088 NOTE: echoing init in image_type does not change it original value.
0089 
0090 Also the driver provides /sys/devices/platform/dell_rbu/data readonly file to
0091 read back the image downloaded.
0092 
0093 NOTE:
0094 This driver requires a patch for firmware_class.c which has the modified
0095 request_firmware_nowait function.
0096 Also after updating the BIOS image a user mode application needs to execute
0097 code which sends the BIOS update request to the BIOS. So on the next reboot
0098 the BIOS knows about the new image downloaded and it updates itself.
0099 Also don't unload the rbu driver if the image has to be updated.
0100