About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Documentation / dell_rbu.txt




Custom Search

Based on kernel version 4.13.3. Page generated on 2017-09-23 13:54 EST.

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

Information is copyright its respective author. All material is available from the Linux Kernel Source distributed under a GPL License. This page is provided as a free service by mjmwired.net.