嵌入式linux系统原理

Chapter

4.

Development

Tools2021/8/131****(Linux

shell

command

list)Using

a

Practical

Project

WorkspaceGNU

Cross-Platform

Development

ToolchainC

Library

AlternativesIntegrated

Development

EnvironmentsTerminal

Emulators4.1UsingaPracticalProjectWorkspace2021/8/132Directorybootldrbuild-toolsdebugdocimageskernelprojectrootfssysappstmptoolsContentThe

bootloader

or

bootloaders

for

your

targetThe

packages

and

directories

needed

to

build

the

cross-platformdevelopment

toolchainThe

debugging

tools

and

all

related

packagesAll

the

documentation

you

will

need

for

your

projectThe

binary

images

of

the

bootloader,

the

kernel,

and

the

root

filesystemready

to

be

used

on

the

targetThe

different

kernel

versions

you

are

evaluating

for

your

targetYour

own

source

code

for

this

projectThe

root

filesystem

as

seen

by

the

target's

kernel

at

runtimeThe

system

applications

required

for

your

targetA

temporary

directory

to

experiment

and

store

transient

filesThe

complete

cross-platform

development

toolchain

and

C

librarythe

environment

variables2021/8/133export

PROJECT=daq-moduleexportPRJROOT=/home/karim/controlproject/${PROJECT}export

TARGET=i386-linuxexport

PREFIX=${PRJROOT}/toolsexport

TARGET_PREFIX=${PREFIX}/${TARGET}export

PATH=${PREFIX}/bin:${PATH}$: cd

$PRJROOT4.2

GNU

Cross-PlatformDevelopment

Toolchain2021/8/134GNU

Toolchain

BasicsKernel

Headers

SetupBinutils

SetupBootstrap

Compiler

SetupC

Library

SetupFull

Compiler

SetupFinalizing

the

Toolchain

Setup4.2.1

GNU

Toolchain

Basics2021/8/135Configuring

and

building

an

appropriate

GNUtoolchain

is

a

complex

and

delicate

operationthat

requires

a

good

understanding

of

thedependencies

between

the

different

softwarepackages

and

their

respective

roles.

Thisknowledge

is

required,

because

the

GNUtoolchain

components

are

developed

and

releasedindependently

from

one

another.4.2.1.1

Component

versionsKernelHostI386TargetPPCbinutils

gcc2.10.1

2.95.3glibc2.2.1PatchesNoPPCPPCI386i386i386ARM2.4.1-rmk12.10.1

2.95.32.13.2.

1

3.2.12.10.1

2.95.32.2.32.3.12.1.3NoNoYes[3]PPCI386ARMMIPS2.10.1

2.95.32.8.1 egcs-1.1.22.2.32.0.6Yes[3]Yes[4]I386SuperH2.11.2

3.0.12.2.4Yes[5]Sparc2021/8/136PPC2.4.02.10.1

2.95.22.1.3No4.2.1.2

Build

requirements2021/8/137To

build

a

cross-platform

development

toolchain,

youwill

need

a

functional

native

toolchain.

Mostmainstream

distributions

provide

this

toolchain

aspart

of

their

packages.

If

it

was

not

installed

on

yourworkstation

or

if

you

chose

not

to

install

it

to

savespace,

you

will

need

to

install

it

at

this

point

using

theprocedure

appropriate

to

your

distribution.

With

aRed

Hat

distribution,

for

instance,

you

will

need

toinstall

the

appropriate

RPM

packages.4.2.1.3

Build

overview2021/8/138With

the

appropriate

tools

in

place,

let

us

take

alook

at

the

procedure

used

to

build

the

toolchain.These

are

the

five

main

steps:Kernel

headers

setupBinary

utilities

setup3.Bootstrap

compiler

setupC

library

setupFull

compiler

setup4.2.2

Kernel

Headers

Setup2021/8/139the

first

thing

you

need

to

do

is

download

a

copyof

that

kernel

into

the

directory

**${PRJROOT}/kernel

;

then

extract

it

using

theappropriate

command.

eg.$

tar

xvzf

linux-2.4.18.tar.gz$

tar

xvjf

linux-2.4.18.tar.bz2

;For

all

kernels

up

to

2.4.18,

the

tar

commandcreates

a

directory

called

linux

that

contains

theextracted

files

from

the

archive.Starting

with

2.4.19,

however,

the

kernel

extracts

immediatelyinto

a

directory

that

has

the

version

number

appended

to

its

name.Hence,

Linux

2.4.19

extracts

directly

into

the

linux-2.4.19directory.

This

avoids

accidently

overwriting

an

older

kernel

witha

new

one.

If

you

are

using

a

kernel

that

is

older

than

2.4.19,

Imend

that

you

rename

the

directory

right

away

to

avoid

anyaccidental

overwriting:$

mv

linux

linux-2.4.18With

the

kernel

now

extracted,

we

proceed

to

configuring

it:$

cd

linux-2.4.18$

make

ARCH=i386CROSS_COMPILE=i386-linux-

menuconfigAs

you

probably

noticed,

the

values

of

ARCH

andCROSS_COMPILE

depend

on

your

target's

architecture

type.Had

this

been

a

PPC

target

and

an

i386

host,

we

would

haveusedARCH=ppc

and

CROSS_COMPILE=powerpc-linux-.2021/8/1310Wecan

now

create

the

include

directory

required

for

the

toolchainand

copy

the

kernel

headers

to

it:$

mkdir

-p

${TARGET_PREFIX}/include$

cp

-r

include/linux/

${TARGET_PREFIX}/include$

cp-r

include/asm-i386/

${TARGET_PREFIX}/include/asm$

cp

-r

include/asm-generic/

${TARGET_PREFIX}/includeKeep

in

mind

that

we

are

using

a

PPC

host

and

an

i386

target.Hence,

the

asm-i386

directory

in

the

path

above

is

the

directorycontaining

the

target-specific

headers,

not

the

host-specific

ones.

Ifthis

were

a

PPC

target,

for

example,

we

would

have

to

replaceasm-i386

with

asm-ppc.2021/8/13114.2.3

Binutils

Setup2021/8/1312The

binutils

package

includes

the

utilities

most

oftenused

to

manipulate

binary

object

files.

The

two

mostimportant

utilities

within

the

package

are

the

GNUassembler,

as,

and

the

linker,

ld.

Others like

follow:gasp

:The

GNU

assembler

pre-processorar

:Creates

and

manipulates

archive

contentnm

:Lists

the

symbols

in

an

object

file…size

:Lists

the

sizes

of

sections

within

an

object

fileThe

first

step

in

setting

up

the

binutils

package

is

to

extract

its

source

codefrom

the

archive

we

downloaded

earlier:$

cd

${PRJROOT}/build-tools$

tar

xvzf

binutils-2.10.1.tar.gzThis

will

create

a

directory

called

binutils-2.10.1

with

the

package'scontent.

We

can

now

move

to

the

build

directory

for

the

second

part

of

thebuild

process,

the

configuration

of

the

package

for

cross-platformdevelopment:$

cd

build-binutils$

../binutils-2.10.1/configure

--target=$TARGET--prefix=${PREFIX}2021/8/1313During

its

run,

configure

checks

for

the

availability

of

certainresources

on

the

host

and

creates

appropriate

Makefiles

foreach

tool

in

the

package.

Since

the

command

is

not

beingissued

in

the

directory

containing

the

binutils

source

code,

the

result

of

the

configure

command

will

be

found

in

thedirectory

where

it

was

issued,

the

build-binutils

directory.With

the

Makefiles

now

ready,

we

can

build

the

actualutilities:$

makeWith

the

package

now

built,

we

can

install

the

binutils:$

make

installThe

binutils

have

now

been

installed

inside

the

directorypointed

to

by

PREFIX.

You

can

check

to

see

that

they

havebeen

installed

properly

by

listing

the

appropriate

directory:2021/8/1314$

ls

${PREFIX}/bini386-linux-addr2line

i386-linux-ld2021/8/1315i386-linux-nmi386-linux-readelfi386-linux-sizei386-linux-ari386-linux-asi386-linux-c++filti386-linux-gaspi386-linux-objcopy

i386-linux-stringsi386-linux-objdump

i386-linux-stripi386-linux-ranlibNotice

that

the

name

of

each

utility

is

prepended

by

thevalue

of

TARGET

we

set

earlier.

Had

the

target

been

apowerpc-linux,

for

instance,

the

names

of

the

utilitieswould

have

been

prepended

with

powerpc-linux-.

Whenbuilding

an

application

for

a

target,

we

can

therefore

usethe

appropriate

tools

by

prepending

the

name

of

the

targettype.4.2.4

Bootstrap

Compiler

SetupIncontrasttothebinutilspackage,thegcc

package

containsonlyone

utility,the

GNUcompiler,alongwithsupportcomponents

such

as

runtimelibraries.At

thisstage,

wewill

buildthebootstrapcompiler,whichwillsupportonlythe

Clanguage.Later,once

the

Clibrary

hasbeen

compiled,we

will

pilegccwithfullC++support.2021/8/1316Again,

we

start

by

extracting

the

gcc

package

from

the

archive

wedownloaded

earlier:$

cd

${PRJROOT}/build-tools$

tar

xvzf

gcc-2.95.3.tar.gzThis

will

create

a

directory

called

gcc-2.95.3

with

the

package'scontent.

We

can

now

proceed

to

the

configuration

of

the

build

in

thedirectory

we

had

prepared

for

the

bootstrap

compiler:$

cd

build-boot-gcc$../gcc-2.95.3/configure--target=$TARGET--prefix=${PREFIX}>

--without-headers

--with-newlib

--enable-languages=cThis

will

print

output

similar

to

that

printed

by

the

binutilsconfiguration

utility

we

discussed

earlier.

Here

too,

configurechecks

for

the

availability

of

resources

and

builds

appropriateMakefiles.2021/8/1317With

the

Makefiles

ready,

we

can

now

build

the

compiler:$

make

all-gccThe

compile

time

for

the

bootstrap

compiler

is

comparableto

that

of

the

binutils.

Here,

too,

you

may

see

warningsduring

the

compilation,

and

you

can

safely

ignore

them.With

the

compilation

complete,

we

can

now

install

gcc:$

make

install-gccThe

bootstrap

compiler

is

now

installed

alongside

thebinutils,

and

you

can

see

it

by

relisting

the

content

of${PREFIX}/bin.

The

name

of

the

compiler,

like

theutilities,

is

prepended

with

the

name

of

the

target

and

iscalled

i386-linux-gcc

in

our

example.2021/8/13184.2.5CLibrarySetup2021/8/1319The

glibc

package

is

made

up

of

a

number

of

libraries

and

isthe

most

delicate

and

lengthy

package

build

in

our

cross-platform

development

toolchain.

It

is

an

extremely

importantsoftware

component

on

which

most,

if

not

all,

applicationsavailable

or

being

developed

for

your

target

will

rely.

Note

thatalthough

the

glibc

package

is

often

called

the

C

library—aconfusion

maintained

within

GNU's

own

documentation—glibc

actually

generates

many

libraries,

one

of

which

is

theactual

C

library,

libc.

We

will

discuss

the

complete

list

oflibraries

generated

by

glibc

in

Chapter

6.

Until

then,

I

willcontinue

to

use

"C

library"

and

"glibc"

interchangeably.20First,

we

must

extract

the

glibc

package

and

its

add-ons,

as

wewould

do

when

setting

up

the

C

library:$

cd

${PRJROOT}/build-tools$

tar

xvzf

glibc-2.3.1.tar.gz$

tar

-xvzf

glibc-linuxthreads-2.3.1.tar.gz

--directory=glibc-2.3.1Next,

we

must

configure

glibc

and

install

its

headers:$mkdir

build-glibc-headers$

cd

build-glibc-headers$

../glibc-2.3.1/configure

--host=$TARGET

--prefix="/usr"

\>

--enable-add-ons

--with-headers=${TARGET_PREFIX}/include$

make

piling=yes

install_root=${TARGET_PREFIX}

\202>1/8p/1r3efix=""

install-headersInstalling

the

headers

is

achieved

by

using

the

install-headersMakefile

target.Next,

we

create

a

dummy

stubs.h

file

required

for

gcc

tobuild

(a

version

of

this

file

will

be

generated

properly

duringthe

installation

of

the piled

glibc):$

mkdir

-p

${TARGET_PREFIX}/include/gnu$

touch

${TARGET_PREFIX}/include/gnu/stubs.hFinally,

we

can

build

the

bootstrap

gcc

compiler:$

cd

${PRJROOT}/build-tools/build-boot-gcc$

../gcc-3.2.1/configure

--target=$TARGET

-->prefix=${PREFIX}

\

--disable-shared

--with->headers=${TARGET_PREFIX}/include

\>

--with-newlib

--enable-languages=c$

make

all-gcc2021/8/13214.2.6

FullCompilerSetup2021/8/1322We

are

now

ready

to

install

the

full

compiler

for

yourtarget

with

both

C

and

C++

support.

Since

we

hadalready

extracted

the

compiler

from

its

archive

inSection

4.2.4,

we

will

not

need

to

repeat

this

step.Overall,

the

build

of

the

full

compiler

is

much

simplerthan

the

build

of

the

bootstrap

compiler.From

the

build-tools/build-gcc

directory

enter:$

cd

${PRJROOT}/build-tools/build-gcc$

../gcc-2.95.3/configure--target=$

TARGET

--prefix=${PREFIX}

\--enable-languages=c,c++$

make

all$

make

install4.2.7

Finalizing

the

Toolchain

Setup2021/8/1323Regardless

of

the

type

of

host

or

the

gcc

version

you

use,

adirectory

similar

to

${PREFIX}/lib/gcc-lib/i386-linux/2.95.3will

be

created

during

the

building

of

the

cross-platformdevelopment

toolchain.

As

you

can

see,

the

directory

path

ismade

up

of

the

target

type

and

the

gcc

version.

Yourparticular

directory

should

be

located

in

${PREFIX}/lib/gcc-lib/${TARGET}/GCC_VERSION,

where

GCC_VERSION

isthe

version

of

gcc

you

are

using

in

your

cross-platformdevelopment

toolchain.4.3CLibraryAlternatives2021/8/1324Given

the

constraints

and

limitations

of

embeddedsystems,

the

size

of

the

standard

GNU

C

librarymakes

it

an

unlikely

candidate

for

use

on

our

target.Instead,

we

need

to

look

for

a

C

library

that

willhave

sufficient

functionality

while

being

relativelysmall.Here

are

the

two

most

important

C

libraryalternatives:

uClibc

and

diet

libc.4.4Integrated

Development

Environments2021/8/1325Many

integrated

development

environments

(IDEs)are

available

for

Linux.

Most

of

these

IDEs

areusually

used

to

develop

native

applications.Nevertheless,

they

can

be

customized

for

cross-development

by

setting

the

appropriate

compilernames

in

the

IDE's

configuration.

Table

4-8

provides

a

list

of

open

source

IDEs,

their

locations,and

the

list

of

embedded

Linux-relevant

programminglanguages

they

support.Table

4-8.

Open

source

IDEs

It

means

free-paymentIDELocationSupportedlanguagesAnjutaAda,

bash,

C,

C++,

Java,

make,

Perl,PythonEclipseC,C++,JavaGlimmerAda,

bash,

C,

C++,

Java,

make,

Perl,Pyt