1 ========================= 2 BOOTING FR-V LINUX KERNEL 3 ========================= 4 5====================== 6PROVIDING A FILESYSTEM 7====================== 8 9First of all, a root filesystem must be made available. This can be done in 10one 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======================== 26LOADING THE KERNEL IMAGE 27======================== 28 29The kernel will need to be loaded into RAM by RedBoot (or by some alternative 30boot loader) before it can be run. The kernel image (arch/frv/boot/Image) may 31be 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================== 67BOOTING THE KERNEL 68================== 69 70Boot the image with the following RedBoot command: 71 72 exec -c "<CMDLINE>" 0x00100000 73 74For example: 75 76 exec -c "console=ttySM0,115200 ip=:::::dhcp root=/dev/mtdblock2 rw" 77 78This will start the kernel running. Note that if the GDB-stub is compiled in, 79then the kernel will immediately wait for GDB to connect over serial before 80doing anything else. See the section on kernel debugging with GDB. 81 82The kernel command line <CMDLINE> tells the kernel where its console is and 83how to find its root filesystem. This is made up of the following components, 84separated 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=/dev/<xxxx> 110 111 This specifies the device upon which the root filesystem resides. For 112 example: 113 114 /dev/nfs NFS root filesystem 115 /dev/mtdblock3 Fourth RedBoot partition on the System Flash 116 117 (*) rw 118 119 Start with the root filesystem mounted Read/Write. 120 121 The remaining components are all optional: 122 123 (*) ip=<ip>::::<host>:<iface>:<cfg> 124 125 Configure the network interface. If <cfg> is "off" then <ip> should 126 specify the IP address for the network device <iface>. <host> provide 127 the hostname for the device. 128 129 If <cfg> is "bootp" or "dhcp", then all of these parameters will be 130 discovered by consulting a BOOTP or DHCP server. 131 132 For example, the following might be used: 133 134 ip=192.168.73.12::::frv:eth0:off 135 136 This sets the IP address on the VDK motherboard RTL8029 ethernet chipset 137 (eth0) to be 192.168.73.12, and sets the board's hostname to be "frv". 138 139 (*) nfsroot=<server>:<dir>[,v<vers>] 140 141 This is mandatory if "root=/dev/nfs" is given as an option. It tells the 142 kernel the IP address of the NFS server providing its root filesystem, 143 and the pathname on that server of the filesystem. 144 145 The NFS version to use can also be specified. v2 and v3 are supported by 146 Linux. 147 148 For example: 149 150 nfsroot=192.168.73.1:/nfsroot-frv 151 152 (*) profile=1 153 154 Turns on the kernel profiler (accessible through /proc/profile). 155 156 (*) console=gdb0 157 158 This can be used as an alternative to the "console=ttyS..." listed 159 above. I tells the kernel to pass the console output to GDB if the 160 gdbstub is compiled in to the kernel. 161 162 If this is used, then the gdbstub passes the text to GDB, which then 163 simply dumps it to its standard output. 164 165 (*) mem=<xxx>M 166 167 Normally the kernel will work out how much SDRAM it has by reading the 168 SDRAM controller registers. That can be overridden with this 169 option. This allows the kernel to be told that it has <xxx> megabytes of 170 memory available. 171 172 (*) init=<prog> [<arg> [<arg> [<arg> ...]]] 173 174 This tells the kernel what program to run initially. By default this is 175 /sbin/init, but /sbin/sash or /bin/sh are common alternatives. 176 177 (*) vdc=... 178 179 This option configures the MB93493 companion chip visual display 180 driver. Please see Documentation/frv/mb93493/vdc.txt for more 181 information. 182