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Based on kernel version 3.15.4. Page generated on 2014-07-07 09:03 EST.

1				  =========================
2				  BOOTING FR-V LINUX KERNEL
3				  =========================
4	
5	======================
6	PROVIDING A FILESYSTEM
7	======================
8	
9	First of all, a root filesystem must be made available. This can be done in
10	one of two ways:
11	
12	  (1) NFS Export
13	
14	      A filesystem should be constructed in a directory on an NFS server that
15	      the target board can reach. This directory should then be NFS exported
16	      such that the target board can read and write into it as root.
17	
18	  (2) Flash Filesystem (JFFS2 Recommended)
19	
20	      In this case, the image must be stored or built up on flash before it
21	      can be used. A complete image can be built using the mkfs.jffs2 or
22	      similar program and then downloaded and stored into flash by RedBoot.
23	
24	
25	========================
26	LOADING THE KERNEL IMAGE
27	========================
28	
29	The kernel will need to be loaded into RAM by RedBoot (or by some alternative
30	boot loader) before it can be run. The kernel image (arch/frv/boot/Image) may
31	be loaded in one of three ways:
32	
33	  (1) Load from Flash
34	
35	      This is the simplest. RedBoot can store an image in the flash (see the
36	      RedBoot documentation) and then load it back into RAM. RedBoot keeps
37	      track of the load address, entry point and size, so the command to do
38	      this is simply:
39	
40		fis load linux
41	
42	      The image is then ready to be executed.
43	
44	  (2) Load by TFTP
45	
46	      The following command will download a raw binary kernel image from the
47	      default server (as negotiated by BOOTP) and store it into RAM:
48	
49		load -b 0x00100000 -r /tftpboot/image.bin
50	
51	      The image is then ready to be executed.
52	
53	  (3) Load by Y-Modem
54	
55	      The following command will download a raw binary kernel image across the
56	      serial port that RedBoot is currently using:
57	
58		load -m ymodem -b 0x00100000 -r zImage
59	
60	      The serial client (such as minicom) must then be told to transmit the
61	      program by Y-Modem.
62	
63	      When finished, the image will then be ready to be executed.
64	
65	
66	==================
67	BOOTING THE KERNEL
68	==================
69	
70	Boot the image with the following RedBoot command:
71	
72		exec -c "<CMDLINE>" 0x00100000
73	
74	For example:
75	
76		exec -c "console=ttySM0,115200 ip=:::::dhcp root=/dev/mtdblock2 rw"
77	
78	This will start the kernel running. Note that if the GDB-stub is compiled in,
79	then the kernel will immediately wait for GDB to connect over serial before
80	doing anything else. See the section on kernel debugging with GDB.
81	
82	The kernel command line <CMDLINE> tells the kernel where its console is and
83	how to find its root filesystem. This is made up of the following components,
84	separated by spaces:
85	
86	  (*) console=ttyS<x>[,<baud>[<parity>[<bits>[<flow>]]]]
87	
88	      This specifies that the system console should output through on-chip
89	      serial port <x> (which can be "0" or "1").
90	
91	      <baud> is a standard baud rate between 1200 and 115200 (default 9600).
92	
93	      <parity> is a parity setting of "N", "O", "E", "M" or "S" for None, Odd,
94	      Even, Mark or Space. "None" is the default.
95	
96	      <stop> is "7" or "8" for the number of bits per character. "8" is the
97	      default.
98	
99	      <flow> is "r" to use flow control (XCTS on serial port 2 only). The
100	      default is to not use flow control.
101	
102	      For example:
103	
104		console=ttyS0,115200
105	
106	      To use the first on-chip serial port at baud rate 115200, no parity, 8
107	      bits, and no flow control.
108	
109	  (*) root=<xxxx>
110	
111	      This specifies the device upon which the root filesystem resides. It
112	      may be specified by major and minor number, device path, or even
113	      partition uuid, if supported.  For example:
114	
115		/dev/nfs	NFS root filesystem
116		/dev/mtdblock3	Fourth RedBoot partition on the System Flash
117		PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF/PARTNROFF=1
118			first partition after the partition with the given UUID
119		253:0		Device with major 253 and minor 0
120	
121	      Authoritative information can be found in
122	      "Documentation/kernel-parameters.txt".
123	
124	  (*) rw
125	
126	      Start with the root filesystem mounted Read/Write.
127	
128	  The remaining components are all optional:
129	
130	  (*) ip=<ip>::::<host>:<iface>:<cfg>
131	
132	      Configure the network interface. If <cfg> is "off" then <ip> should
133	      specify the IP address for the network device <iface>. <host> provide
134	      the hostname for the device.
135	
136	      If <cfg> is "bootp" or "dhcp", then all of these parameters will be
137	      discovered by consulting a BOOTP or DHCP server.
138	
139	      For example, the following might be used:
140	
141		ip=192.168.73.12::::frv:eth0:off
142	
143	      This sets the IP address on the VDK motherboard RTL8029 ethernet chipset
144	      (eth0) to be 192.168.73.12, and sets the board's hostname to be "frv".
145	
146	  (*) nfsroot=<server>:<dir>[,v<vers>]
147	
148	      This is mandatory if "root=/dev/nfs" is given as an option. It tells the
149	      kernel the IP address of the NFS server providing its root filesystem,
150	      and the pathname on that server of the filesystem.
151	
152	      The NFS version to use can also be specified. v2 and v3 are supported by
153	      Linux.
154	
155	      For example:
156	
157		nfsroot=192.168.73.1:/nfsroot-frv
158	
159	  (*) profile=1
160	
161	      Turns on the kernel profiler (accessible through /proc/profile).
162	
163	  (*) console=gdb0
164	
165	      This can be used as an alternative to the "console=ttyS..." listed
166	      above. I tells the kernel to pass the console output to GDB if the
167	      gdbstub is compiled in to the kernel.
168	
169	      If this is used, then the gdbstub passes the text to GDB, which then
170	      simply dumps it to its standard output.
171	
172	  (*) mem=<xxx>M
173	
174	      Normally the kernel will work out how much SDRAM it has by reading the
175	      SDRAM controller registers. That can be overridden with this
176	      option. This allows the kernel to be told that it has <xxx> megabytes of
177	      memory available.
178	
179	  (*) init=<prog> [<arg> [<arg> [<arg> ...]]]
180	
181	      This tells the kernel what program to run initially. By default this is
182	      /sbin/init, but /sbin/sash or /bin/sh are common alternatives.
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