linux/Documentation/dell_rbu.txt
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   1Purpose:
   2Demonstrate the usage of the new open sourced rbu (Remote BIOS Update) driver
   3for updating BIOS images on Dell servers and desktops.
   4
   5Scope:
   6This document discusses the functionality of the rbu driver only.
   7It does not cover the support needed from applications to enable the BIOS to
   8update itself with the image downloaded in to the memory.
   9
  10Overview:
  11This driver works with Dell OpenManage or Dell Update Packages for updating
  12the BIOS on Dell servers (starting from servers sold since 1999), desktops
  13and notebooks (starting from those sold in 2005).
  14Please go to  http://support.dell.com register and you can find info on
  15OpenManage and Dell Update packages (DUP).
  16Libsmbios can also be used to update BIOS on Dell systems go to
  17http://linux.dell.com/libsmbios/ for details.
  18
  19Dell_RBU driver supports BIOS update using the monolithic image and packetized
  20image methods. In case of monolithic the driver allocates a contiguous chunk
  21of physical pages having the BIOS image. In case of packetized the app
  22using the driver breaks the image in to packets of fixed sizes and the driver
  23would place each packet in contiguous physical memory. The driver also
  24maintains a link list of packets for reading them back.
  25If the dell_rbu driver is unloaded all the allocated memory is freed.
  26
  27The rbu driver needs to have an application (as mentioned above)which will
  28inform the BIOS to enable the update in the next system reboot.
  29
  30The user should not unload the rbu driver after downloading the BIOS image
  31or updating.
  32
  33The driver load creates the following directories under the /sys file system.
  34/sys/class/firmware/dell_rbu/loading
  35/sys/class/firmware/dell_rbu/data
  36/sys/devices/platform/dell_rbu/image_type
  37/sys/devices/platform/dell_rbu/data
  38/sys/devices/platform/dell_rbu/packet_size
  39
  40The driver supports two types of update mechanism; monolithic and packetized.
  41These update mechanism depends upon the BIOS currently running on the system.
  42Most of the Dell systems support a monolithic update where the BIOS image is
  43copied to a single contiguous block of physical memory.
  44In case of packet mechanism the single memory can be broken in smaller chunks
  45of contiguous memory and the BIOS image is scattered in these packets.
  46
  47By default the driver uses monolithic memory for the update type. This can be
  48changed to packets during the driver load time by specifying the load
  49parameter image_type=packet.  This can also be changed later as below
  50echo packet > /sys/devices/platform/dell_rbu/image_type
  51
  52In packet update mode the packet size has to be given before any packets can
  53be downloaded. It is done as below
  54echo XXXX > /sys/devices/platform/dell_rbu/packet_size
  55In the packet update mechanism, the user needs to create a new file having
  56packets of data arranged back to back. It can be done as follows
  57The user creates packets header, gets the chunk of the BIOS image and
  58places it next to the packetheader; now, the packetheader + BIOS image chunk
  59added together should match the specified packet_size. This makes one
  60packet, the user needs to create more such packets out of the entire BIOS
  61image file and then arrange all these packets back to back in to one single
  62file.
  63This file is then copied to /sys/class/firmware/dell_rbu/data.
  64Once this file gets to the driver, the driver extracts packet_size data from
  65the file and spreads it across the physical memory in contiguous packet_sized
  66space.
  67This method makes sure that all the packets get to the driver in a single operation.
  68
  69In monolithic update the user simply get the BIOS image (.hdr file) and copies
  70to the data file as is without any change to the BIOS image itself.
  71
  72Do the steps below to download the BIOS image.
  731) echo 1 > /sys/class/firmware/dell_rbu/loading
  742) cp bios_image.hdr /sys/class/firmware/dell_rbu/data
  753) echo 0 > /sys/class/firmware/dell_rbu/loading
  76
  77The /sys/class/firmware/dell_rbu/ entries will remain till the following is
  78done.
  79echo -1 > /sys/class/firmware/dell_rbu/loading
  80Until this step is completed the driver cannot be unloaded.
  81Also echoing either mono, packet or init in to image_type will free up the
  82memory allocated by the driver.
  83
  84If a user by accident executes steps 1 and 3 above without executing step 2;
  85it will make the /sys/class/firmware/dell_rbu/ entries disappear.
  86The entries can be recreated by doing the following
  87echo init > /sys/devices/platform/dell_rbu/image_type
  88NOTE: echoing init in image_type does not change it original value.
  89
  90Also the driver provides /sys/devices/platform/dell_rbu/data readonly file to
  91read back the image downloaded.
  92
  93NOTE:
  94This driver requires a patch for firmware_class.c which has the modified
  95request_firmware_nowait function.
  96Also after updating the BIOS image a user mode application needs to execute
  97code which sends the BIOS update request to the BIOS. So on the next reboot
  98the BIOS knows about the new image downloaded and it updates itself.
  99Also don't unload the rbu driver if the image has to be updated.
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