Documentation/frv/booting.txt

   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.