183 lines
5.8 KiB
Plaintext
183 lines
5.8 KiB
Plaintext
=========================
|
|
BOOTING FR-V LINUX KERNEL
|
|
=========================
|
|
|
|
======================
|
|
PROVIDING A FILESYSTEM
|
|
======================
|
|
|
|
First of all, a root filesystem must be made available. This can be done in
|
|
one of two ways:
|
|
|
|
(1) NFS Export
|
|
|
|
A filesystem should be constructed in a directory on an NFS server that
|
|
the target board can reach. This directory should then be NFS exported
|
|
such that the target board can read and write into it as root.
|
|
|
|
(2) Flash Filesystem (JFFS2 Recommended)
|
|
|
|
In this case, the image must be stored or built up on flash before it
|
|
can be used. A complete image can be built using the mkfs.jffs2 or
|
|
similar program and then downloaded and stored into flash by RedBoot.
|
|
|
|
|
|
========================
|
|
LOADING THE KERNEL IMAGE
|
|
========================
|
|
|
|
The kernel will need to be loaded into RAM by RedBoot (or by some alternative
|
|
boot loader) before it can be run. The kernel image (arch/frv/boot/Image) may
|
|
be loaded in one of three ways:
|
|
|
|
(1) Load from Flash
|
|
|
|
This is the simplest. RedBoot can store an image in the flash (see the
|
|
RedBoot documentation) and then load it back into RAM. RedBoot keeps
|
|
track of the load address, entry point and size, so the command to do
|
|
this is simply:
|
|
|
|
fis load linux
|
|
|
|
The image is then ready to be executed.
|
|
|
|
(2) Load by TFTP
|
|
|
|
The following command will download a raw binary kernel image from the
|
|
default server (as negotiated by BOOTP) and store it into RAM:
|
|
|
|
load -b 0x00100000 -r /tftpboot/image.bin
|
|
|
|
The image is then ready to be executed.
|
|
|
|
(3) Load by Y-Modem
|
|
|
|
The following command will download a raw binary kernel image across the
|
|
serial port that RedBoot is currently using:
|
|
|
|
load -m ymodem -b 0x00100000 -r zImage
|
|
|
|
The serial client (such as minicom) must then be told to transmit the
|
|
program by Y-Modem.
|
|
|
|
When finished, the image will then be ready to be executed.
|
|
|
|
|
|
==================
|
|
BOOTING THE KERNEL
|
|
==================
|
|
|
|
Boot the image with the following RedBoot command:
|
|
|
|
exec -c "<CMDLINE>" 0x00100000
|
|
|
|
For example:
|
|
|
|
exec -c "console=ttySM0,115200 ip=:::::dhcp root=/dev/mtdblock2 rw"
|
|
|
|
This will start the kernel running. Note that if the GDB-stub is compiled in,
|
|
then the kernel will immediately wait for GDB to connect over serial before
|
|
doing anything else. See the section on kernel debugging with GDB.
|
|
|
|
The kernel command line <CMDLINE> tells the kernel where its console is and
|
|
how to find its root filesystem. This is made up of the following components,
|
|
separated by spaces:
|
|
|
|
(*) console=ttyS<x>[,<baud>[<parity>[<bits>[<flow>]]]]
|
|
|
|
This specifies that the system console should output through on-chip
|
|
serial port <x> (which can be "0" or "1").
|
|
|
|
<baud> is a standard baud rate between 1200 and 115200 (default 9600).
|
|
|
|
<parity> is a parity setting of "N", "O", "E", "M" or "S" for None, Odd,
|
|
Even, Mark or Space. "None" is the default.
|
|
|
|
<stop> is "7" or "8" for the number of bits per character. "8" is the
|
|
default.
|
|
|
|
<flow> is "r" to use flow control (XCTS on serial port 2 only). The
|
|
default is to not use flow control.
|
|
|
|
For example:
|
|
|
|
console=ttyS0,115200
|
|
|
|
To use the first on-chip serial port at baud rate 115200, no parity, 8
|
|
bits, and no flow control.
|
|
|
|
(*) root=<xxxx>
|
|
|
|
This specifies the device upon which the root filesystem resides. It
|
|
may be specified by major and minor number, device path, or even
|
|
partition uuid, if supported. For example:
|
|
|
|
/dev/nfs NFS root filesystem
|
|
/dev/mtdblock3 Fourth RedBoot partition on the System Flash
|
|
PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF/PARTNROFF=1
|
|
first partition after the partition with the given UUID
|
|
253:0 Device with major 253 and minor 0
|
|
|
|
Authoritative information can be found in
|
|
"Documentation/kernel-parameters.txt".
|
|
|
|
(*) rw
|
|
|
|
Start with the root filesystem mounted Read/Write.
|
|
|
|
The remaining components are all optional:
|
|
|
|
(*) ip=<ip>::::<host>:<iface>:<cfg>
|
|
|
|
Configure the network interface. If <cfg> is "off" then <ip> should
|
|
specify the IP address for the network device <iface>. <host> provide
|
|
the hostname for the device.
|
|
|
|
If <cfg> is "bootp" or "dhcp", then all of these parameters will be
|
|
discovered by consulting a BOOTP or DHCP server.
|
|
|
|
For example, the following might be used:
|
|
|
|
ip=192.168.73.12::::frv:eth0:off
|
|
|
|
This sets the IP address on the VDK motherboard RTL8029 ethernet chipset
|
|
(eth0) to be 192.168.73.12, and sets the board's hostname to be "frv".
|
|
|
|
(*) nfsroot=<server>:<dir>[,v<vers>]
|
|
|
|
This is mandatory if "root=/dev/nfs" is given as an option. It tells the
|
|
kernel the IP address of the NFS server providing its root filesystem,
|
|
and the pathname on that server of the filesystem.
|
|
|
|
The NFS version to use can also be specified. v2 and v3 are supported by
|
|
Linux.
|
|
|
|
For example:
|
|
|
|
nfsroot=192.168.73.1:/nfsroot-frv
|
|
|
|
(*) profile=1
|
|
|
|
Turns on the kernel profiler (accessible through /proc/profile).
|
|
|
|
(*) console=gdb0
|
|
|
|
This can be used as an alternative to the "console=ttyS..." listed
|
|
above. I tells the kernel to pass the console output to GDB if the
|
|
gdbstub is compiled in to the kernel.
|
|
|
|
If this is used, then the gdbstub passes the text to GDB, which then
|
|
simply dumps it to its standard output.
|
|
|
|
(*) mem=<xxx>M
|
|
|
|
Normally the kernel will work out how much SDRAM it has by reading the
|
|
SDRAM controller registers. That can be overridden with this
|
|
option. This allows the kernel to be told that it has <xxx> megabytes of
|
|
memory available.
|
|
|
|
(*) init=<prog> [<arg> [<arg> [<arg> ...]]]
|
|
|
|
This tells the kernel what program to run initially. By default this is
|
|
/sbin/init, but /sbin/sash or /bin/sh are common alternatives.
|