182 lines
5.6 KiB
Plaintext
182 lines
5.6 KiB
Plaintext
=========================
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BOOTING FR-V LINUX KERNEL
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=========================
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======================
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PROVIDING A FILESYSTEM
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======================
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First of all, a root filesystem must be made available. This can be done in
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one of two ways:
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(1) NFS Export
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A filesystem should be constructed in a directory on an NFS server that
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the target board can reach. This directory should then be NFS exported
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such that the target board can read and write into it as root.
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(2) Flash Filesystem (JFFS2 Recommended)
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In this case, the image must be stored or built up on flash before it
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can be used. A complete image can be built using the mkfs.jffs2 or
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similar program and then downloaded and stored into flash by RedBoot.
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========================
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LOADING THE KERNEL IMAGE
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========================
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The kernel will need to be loaded into RAM by RedBoot (or by some alternative
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boot loader) before it can be run. The kernel image (arch/frv/boot/Image) may
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be loaded in one of three ways:
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(1) Load from Flash
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This is the simplest. RedBoot can store an image in the flash (see the
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RedBoot documentation) and then load it back into RAM. RedBoot keeps
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track of the load address, entry point and size, so the command to do
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this is simply:
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fis load linux
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The image is then ready to be executed.
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(2) Load by TFTP
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The following command will download a raw binary kernel image from the
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default server (as negotiated by BOOTP) and store it into RAM:
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load -b 0x00100000 -r /tftpboot/image.bin
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The image is then ready to be executed.
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(3) Load by Y-Modem
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The following command will download a raw binary kernel image across the
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serial port that RedBoot is currently using:
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load -m ymodem -b 0x00100000 -r zImage
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The serial client (such as minicom) must then be told to transmit the
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program by Y-Modem.
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When finished, the image will then be ready to be executed.
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==================
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BOOTING THE KERNEL
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==================
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Boot the image with the following RedBoot command:
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exec -c "<CMDLINE>" 0x00100000
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For example:
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exec -c "console=ttySM0,115200 ip=:::::dhcp root=/dev/mtdblock2 rw"
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This will start the kernel running. Note that if the GDB-stub is compiled in,
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then the kernel will immediately wait for GDB to connect over serial before
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doing anything else. See the section on kernel debugging with GDB.
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The kernel command line <CMDLINE> tells the kernel where its console is and
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how to find its root filesystem. This is made up of the following components,
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separated by spaces:
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(*) console=ttyS<x>[,<baud>[<parity>[<bits>[<flow>]]]]
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This specifies that the system console should output through on-chip
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serial port <x> (which can be "0" or "1").
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<baud> is a standard baud rate between 1200 and 115200 (default 9600).
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<parity> is a parity setting of "N", "O", "E", "M" or "S" for None, Odd,
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Even, Mark or Space. "None" is the default.
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<stop> is "7" or "8" for the number of bits per character. "8" is the
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default.
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<flow> is "r" to use flow control (XCTS on serial port 2 only). The
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default is to not use flow control.
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For example:
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console=ttyS0,115200
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To use the first on-chip serial port at baud rate 115200, no parity, 8
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bits, and no flow control.
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(*) root=/dev/<xxxx>
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This specifies the device upon which the root filesystem resides. For
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example:
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/dev/nfs NFS root filesystem
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/dev/mtdblock3 Fourth RedBoot partition on the System Flash
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(*) rw
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Start with the root filesystem mounted Read/Write.
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The remaining components are all optional:
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(*) ip=<ip>::::<host>:<iface>:<cfg>
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Configure the network interface. If <cfg> is "off" then <ip> should
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specify the IP address for the network device <iface>. <host> provide
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the hostname for the device.
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If <cfg> is "bootp" or "dhcp", then all of these parameters will be
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discovered by consulting a BOOTP or DHCP server.
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For example, the following might be used:
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ip=192.168.73.12::::frv:eth0:off
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This sets the IP address on the VDK motherboard RTL8029 ethernet chipset
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(eth0) to be 192.168.73.12, and sets the board's hostname to be "frv".
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(*) nfsroot=<server>:<dir>[,v<vers>]
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This is mandatory if "root=/dev/nfs" is given as an option. It tells the
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kernel the IP address of the NFS server providing its root filesystem,
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and the pathname on that server of the filesystem.
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The NFS version to use can also be specified. v2 and v3 are supported by
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Linux.
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For example:
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nfsroot=192.168.73.1:/nfsroot-frv
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(*) profile=1
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Turns on the kernel profiler (accessible through /proc/profile).
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(*) console=gdb0
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This can be used as an alternative to the "console=ttyS..." listed
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above. I tells the kernel to pass the console output to GDB if the
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gdbstub is compiled in to the kernel.
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If this is used, then the gdbstub passes the text to GDB, which then
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simply dumps it to its standard output.
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(*) mem=<xxx>M
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Normally the kernel will work out how much SDRAM it has by reading the
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SDRAM controller registers. That can be overridden with this
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option. This allows the kernel to be told that it has <xxx> megabytes of
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memory available.
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(*) init=<prog> [<arg> [<arg> [<arg> ...]]]
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This tells the kernel what program to run initially. By default this is
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/sbin/init, but /sbin/sash or /bin/sh are common alternatives.
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(*) vdc=...
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This option configures the MB93493 companion chip visual display
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driver. Please see Documentation/fujitsu/mb93493/vdc.txt for more
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information.
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