Based on kernel version 4.16.1. Page generated on 2018-04-09 11:53 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/admin-guide/kernel-parameters.rst". 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.