Transcript A Short Introduction to Linux

Education
Outline
• Overview of the uCdimm/uClinux
Development Environment
• Configuring the uCdimm/uClinux
• Write a “C” code using the General Purpose
Parallel I/O
• Overview of the File System Hierarchy in
uClinux
Overview of the
uCdimm/uClinux
Development Environment
Outline
• What is uCdimm?
• What is uCgarderner?
• Overview of Development Environment
• Overview of Development Process
What is uCdimm?
• uCdimm is “uc68VZ328 Microcontroller Module”
DRAM
33MHz
Ethernet
Controller
FLASH
CPU
ROM
DragonBall
2Mb
68VZ328
8Mb
What is uCgardener?
• uCgardener provides power and connecting interface
for uCdimm
RJ45
DB9 serial
Ethernet jack
connector
Power jack and on
board regulator
Overview of Development
Environment (1)
RS-232
+
The connection between host computer and uCdimm
plus uCgardener is made through serial port when
running boot loader.
Overview of Development
Environment (2)
RS-232
+
Ethernet
The connection between host computer and uCdimm
plus uCgardener is made through serial port and
ether net when the uClinux boots.
Overview of Development
Process
•
Kernel Image is generated on host computer
using cross-compiler.
•
Kernel Image is uploaded to uCdimm through
serial port when running boot loader.
•
Kernel Image is uploaded to uCdimm through
ethernet when uClinux boots.
•
Bootloader can boot uClinux kernel ether from
flash ROM or memory.
Configuring the
uCdimm/uClinux
Outline
• Configuring the Linux Workstation
• Configuring the uCdimm Target
• Getting the Serial Connection Up and Running
• Getting the Ethernet Connection Up and Running
• Activities/Exercises
Configuring the Linux Workstation
• Installing the tool chains
• Setting up the working environment
• Configuring Development Environment
Installing the Tool Chains (1)
– For the libc6 case, become root and
• Mount the uClinux CD, eg “mount /dev/cdrom
/mnt/cdrom”
• change into the libc6 directory, eg “cd
/mnt/cdrom/RPM/libc6”
• then do a make, ie “make”
– Some items can be found at /opt/uClinux
bin/
include/
linux/
man/
deftemplat.sh* info/
m68-coff/
romdisk/
dev/
lib/
m68-pic-coff/ src/
Setting up the Working Environment
(1)
•
With the tool chains installed, you can create your working
environment :
– Make a directory to hold your work
– Change to that directory
– Then issue the ‘buildenv’ command
– Finally issue the ‘make’ command
For example :
• mkdir /tmp/uCsimm_work
• cd /tmp/uCsimm_work
• buildenv
• make
Setting up the Working Environment
(2)
•
After issuing make command, we can find something at your
working directory:
Makefile
deftemplate.sh
image.bin
linux
romdisk/
src/
romdisk.map
romdisk.img
Configuring the uCsimm Target
• Power adapter
• The RS232 serial connection
• The Ethernet connection
Getting the Serial Connection Up
and Running
• Using a ‘straight through’ (not null modem) cable,
connect your workstation to your uCgardener.
• Setting up minicom and the serial connection
• Booting uClinux
• Uploading a new OS image
Setting up minicom and serial
connection (1)
Setup minicom parameters:
– Choose the Serial port setup and within that choice :
• Select your Serial Device ( e.g. /dev/ttyS0 )
• Next set your Bps/Par/Bits as 19200 8N1
• Finally say no (N) to both Hardware and
Software Flow Control
Setting up minicom and serial
connection (2)
• Setup minicom parameters: (continued…)
– Choose Modem and dialing and within that
choice
• remove the Init string
• remove the Reset string
– Set minicom to use ‘sz –X’ for XMODEM
protocol.
Bootloader Commands (1)
• help
– Print a list of commands with short descriptions
• rx
– Receive a binary image via the RS232 port using XMODEM protocol
– Store the new image starting at DRAM address 0x00020000.
• program
– Erase an area of the FLASH ROM starting at 0x10C10000.
– Write the image currently in DRAM into that area of the FLASH.
• The image is presumably one that was received into DRAM via the rx command
Bootloader Commands (2)
•
go
– Execute the image residing in the OS area of the FLASH ROM
•
goram
– Execute the image residing in DRAM, presumably one that has been
received via the rx command
•
md address [endaddress]
– Display a memory dump in hexadecimal, starting at address and ending at
endaddress.
•
mm address values…
– Starting at address, sequentially write a byte at a time from values into
memory.
•
mm 00020000 123456
– 0x12 into 0x00020000
– 0x34 into 0x00020001
– 0x56 into 0x00020002
Bootloader Commands (3)
• fast
– Change the serial speed to 115200 bps
Booting uClinux
• bootloader’s B$ prompt
– B$ go
• Login
– uCsimm login: root
– Password: uClinux
• “ls” command
Uploading a new OS image (1)
• Upload a new image at
– 19200bps (slow) or
– 115,200bps (fast)
• Slow
– At the B$ prompt type rx.
B$ rx
– Press ctrl-a and the z to enter the “Minicom Command Summary”
screen
– Choose s for Send files, the as prompted choose the xmodem for
upload protocol
– Next you’ll be prompted for the filename
Upload a new OS image (2)
• To move the just uploaded image to FLASH ROM
– B$ program
Getting the Ethernet Connection Up
and Running
• Configuring nfs on the Linux Workstation
• Setting up the network parameters on your Linux
workstation
• Transferring uClinux images aided by nfs
Setting up the network parameters
on your Linux workstation (1)
• The network environment setup
– Linux workstation
• IP address = 192.168.1.100
• network mask = 255.255.255.0
• network address = 192.168.1.0
• gateway address = 192.168.1.254
• nfs service enable
Setting up the network parameters
on your Linux workstation (2)
NFS server setup
– Add the following line to /etc/exports to tell the nfs server
what files it may export for external mounting. For
example, /nfsroot is the nfs exported directory,
/nfsroot (ro)
– Stop and start the nfs server
/etc/rc.d/init.d/nfs stop
/etc/rc.d/init.d/nfs start
/etc/rc.d/init.d/nfs restart
Configuration the uCdimm Target
(1)
•
The network environment setup
– uCsimm
• IP address = 192.168.1.200
• network mask = 255.255.255.0
• network address = 192.168.1.0
• gateway address = 192.168.1.254
• DNS address = 203.77.1.20
– Mount the nfs directory
• /bin/mount -t nfs 192.168.1.100:/nfsroot /usr
Configuration the uCsimm Target
(2)
•
Modify the /etc/rc file
# attach the interfaces
/sbin/ifattach
/sbin/ifattach \
--addr 192.168.1.200 \
--mask 255.255.255.0 \
--net 192.168.1.0 \
--gw 192.168.1.254 eth0
# expand the ramdisk
/sbin/expand /ramfs.img /dev/ram0
(continued…)
Configuration the uCsimm Target
(3)
•
Modify the /etc/rc file ( continued … )
# mount ramdisk, proc and nfs
/bin/mount -t ext2 /dev/ram0 /var
/bin/mount -t proc proc /proc
/bin/mount -t nfs 192.168.1.100:/nfsroot /usr
# start up the internet superserver
/sbin/inetd &
# that's it... sucess
exit 0
–flashloader
A Example : Make a New Image
• Change the default password
– Modify the src/init/login.c, line #24
• Make a new image, enter ‘make’
• Copy the new image, image.bin, to /nfsroot
– cp image.bin /nfsroot
• Boot up the uCdimm
• On the uCdimm, mount the nfs filesystem
– mount –t nfs 192.168.1.100:/nfsroot /usr
• Download and flash the new image
– flashloader /usr/image.bin
Using the General Purpose
Parallel I/O
OUTLINE
• Introduction
• Example Programs using Port D I/O
• Running the Example Programs
• Primitives for an I/O Control Language
• Activities / Exercise
Introduction
• Circuitry has been added to the uCgardener to
make Port D available as input and output.
– Available 8 output leds and 8 input switch
– Negative logic
• 1: off
• 0: on
Example Programs
using Port D I/O
• Program #1 – output only, turns on leds
Example Program #1 – Write Port D
/*
* file: write_led.c
*/
#include <asm/MC68EZ328.h>
void init_portd(void)
{
PDSEL = 0xFF;
/* select port D for I/O */
PDDIR = 0xFF;
/* set bits 0-7 as output */
PDDATA = 0xFF;
/* initialize to off */
} /* init_portd() */
Example Program #1 – Write Port D
(cont’d)
int write_output_portd(unsigned int which_bit)
{
unsigned char temp;
if (which_bit > 7) return –1;
temp = 0x01 << which_bit;
PDDATA = PDDATA & ~temp;
if (temp == 0)
return 0;
else
return 1;
} /* write_output_portd() */
Example Program #1 – Write Port D
(cont’d)
int main(void)
{
unsigned int out_led;
int
result;
init_portd();
while (1) {
printf(“\nWhich led[range 0->7] shall we turn on?\n”);
scanf(“%d”, &out_led);
result = write_output_portd(out_led);
if (result < 0) {
printf(“Invalid led number\n”);
continue;
}
}
} /* main() */
Running from a Testing
Environment (cont’d)
• The steps to running write_led
– On the host, create the program file in working directory
– On the host, compile the program file
• m68k-pic-coff-gcc write_led.c –o write_led
– From your serial terminal, run the program on the target
with the working directory
The File System Hierarchy
in uClinux
The File System Hierarchy
Standard (1/3)
Directory
Directory Purpose/Contents
Name
bin
essential command binaries which may be used by the
system administrator and by ordinary users, required for
system boot
boot
kernel image and configuration files used by the boot
dev
devices files
etc
host-specific configuration files
home
user home directories
The File System Hierarchy
Standard (2/3)
lib
essential shared libraries and kernel modules
mnt
mount point for temporarily mounting file system such as
those on a CDROM or floppy disk
opt
add-on application software packages
root
the root user’s home directory
sbin
system binaries, essential for system administration, but
not for system boot
The File System Hierarchy
Standard (3/3)
tmp
location of temporary files
user
secondary hierarchy, intended as shareable, read-only
data. Here you’ll find games, include files used by C
programs, the linux source code hierarchy, and so on.
var
variable data such as spool directories and log files
The File System Hierarchy in
uClinux (1/2)
Directory
Directory Purpose/Contents
Name
bin
per the standard
dev
per the standard
etc
per the standard
htdocs
when the uClinux is accessed via ethernet using http, this
is the directory accessed
lib
contains liberror.txt, a file containing text for a variety of
error messages
The File System Hierarchy in
uClinux (2/2)
proc
traditional
sbin
per the standard
tmp
a link to /var/tmp
usr
empty, suggested as the mount point for
var
presumably per the standard, but empty except for
lost+found