多核操作系统实践 实验一.docx

多核操作系统实践 实验一.docx

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多核操作系统实践实验一

多核操作系统实践实验一

作者：

卓达城

说明：

由于在linux上打中文太麻烦，虽然本人英文不好，不过还是用英文写，部分地方中文注释。

^^^^^^^^^^^^^^^^^^^^^^^^^PART1^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

首先要做的是安装开发环境。

下载VMware，Ubuntu并安装。

然后下载bochs的源代码，编译安装，编译bochs需要安装几个依赖包。

依赖包包括：

build-essential，xorg-dev，pkg-config，gtk2.0

编译JOS。

编译完之后，修改bochs的配置文件（具体两处），使JOS在bochs中启动。

具体步骤如下：

Firstweneedtoinstallthedevelopmentenvironment.

1.installvmware7.1inwindowsthencreatethevirtualmachineforlinux（ubuntu）

2.installubuntu10.4inthevirtualmachine

3.setthechineseeducationnetworkupdatesourceinubuntu10.4

（设置教育网的linux更新源，不然以现在的网速更新实在令人受不了）

Howtosetit?

google!

4.installbuild-essential:

usingtheubuntusoftwarecentertoinstallthe"build-essential".Youcantypebuild-essentialinthesoftwarecentersearchbar,theninstallthebuild-essential.Becauseofmycomputerissoslowlytoopenthesoftwarecenter,soiuseapt-gettoinstallit.

thecommandis:

sudoapt-getinstallbuild-essential

5.installxorg-dev

thecommandis:

sudoapt-getinstallxorg-dev

6.installpkg-config

thecommandis:

sudoapt-getinstallpkg-config

7.installgtk2.0

thecommandis:

sudoapt-getinstalllibgtk2.0-dev

8.

Downloadthebochsfromourteacher'swebsite.Thenextractittoyourfavouritefolder.

9.

Compilethebochs

Gotothefolderthatyouplacethebochsthen

Typecommand:

./configure--prefix=/usr--enable-disasm--enable-debugger

Iwillinstallbochsinusr.ifinstallinotherfolder,youmayhavetosettheenviromnent.

Typecommand:

make

wait.......

Typecommand:

sudomakeinstall

10.

CompiletheJOS

Downloadthelab1.tar.gzfromourteacher'swebsite

Extractthem.

Ifyouwanttousegmaketypecommand:

ln-s/usr/bin/make/usr/bin/gmake

Ifyouusemakethenyouhavenoneedtodothestepabove

Gotothefolderlab1

typecommand:

make

ortype:

gmake

11.

Editthebochsconfigfile.bochsrc

Thisfileisinthefolderlab1,butitishidden.Youmustcheckedthe"ShowHiddenfiles"（文件是隐藏的，要显示隐藏文件才能看到）

---------------------------------------------------------------------

Openitandfindthestring:

ata0-master:

type=disk,mode=flat,path="./obj/kern/bochs.img",cylinders=100,heads=10,spt=10

Repalceitwith:

ata0-master:

type=disk,mode=flat,path="*******/obj/kern/bochs.img",cylinders=100,heads=10,spt=10

*******isthepathoftheobjfolder'path.

Example:

/home/zdc/labs/lab1/lab1/obj/kern/bochs.img

---------------------------------------------------------------------

Findthestring:

romimage:

file=$BXSHARE/BIOS-bochs-latest,address=0xf0000

Replaceitwith:

romimage:

file=$BXSHARE/BIOS-bochs-latest

12

Runbochs

Thentype2tosetthepathofthe.bochsrc

Ifsuccesstype6

ThenweruntheJOSsuccessfully.

GoodLuck!

!

!

SecondwefinishtheExercise

Exercise1

Learnthex86assemberLanguage

LearntheAT&TassemberLanguage

Exercise2

Familiarwithbochsandbochsdebugger.

Themostusefulcommandsares,c,u/naddress,q,baddress

Exercise3

Understandwhatisthebiosdoing.

Biossetstheidtfirst,initializesthekeydevicesandthenjumpto0000:

7c00

启动的过程：

CPU加电后从地址0xfffffff0开始运行，这个地址指向BIOS的ROM部分。

BIOS先设置中断表，然后检测和初始化关键设备，然后把硬盘的第一个块加载到0x00007c00运行（这里就是我们JOS的boot）。

^^^^^^^^^^^^^^^^^^^^^^^^^PART2^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

第二部分主要是要我们熟悉bochs的调试工作。

Exercise4

Setthebreakpointin0000:

7c00andtraceit.

Wecanusesperformthecommandstepandstep.

Orwecanuseu/naddresstoseeninstructionsstartfromtheaddress

Thedebuggercommandsimples:

b0x0000:

0x7c00

s

u/100x00:

0x7c00

Tracebootmain（）linenumber：

100inboot.S

Throughreadtheboot.asm,Wecanknowthatfunctionbootmainwillbecalledin0x0000:

0x7c45（0008:

00007c45）.Sowesetthebreakpointin0x0000:

0x7c40,thentypes.Orsetthebreakpointin0x0000:

0x7c45directly.

Tracereadseg（）反汇编boot/main.ocommandobjdump-Smain.o-Mintel>main.asm

Throughtracingtheinstructionsperforminbootmain（）,wefindthefunctionreadseg（）iscalledat0x0000:

0x7d33（0008:

00007d33）.

Startat7ce3:

55push%ebp

endat0x7d21

readsect（）

Thisfunctioniscalledat[0x00007d0f]0008:

00007d0f,theinstructionis:

call7c81

Startat"7c81:

55push%ebp"

Thisfunctionendat[0x00007ce2]0008:

00007ce2（unk.ctxt）:

ret

Afterthisfunction,theesppointto0x7d14

Thenperformserveralinstructionsuntil"7d16:

39fbcmp%edi,%ebx"

Thisinstructionjudgethecondictiontodecidewhethercontinuetojumpto0x7d06,therearesomeinstructionstosettheparametersforreadsectfrom7d06to7d0f

Atexactlywhatpointdoestheprocessortransitionfromexecuting16-bitcodetoexecuting32-bitcode?

movl%cr0,%eax

orl$CR0_PE_ON,%eax

movl%eax,%cr0

[0x00007c2a]0000:

7c2a（unk.ctxt）:

movcr0,eax

thisinstructionstarttheprotectmodule

Whatisthelastinstructionofthebootloaderexecuted,andwhatisthefirstinstructionofthekernelitjustloaded?

Thebootloader'slastinstructionis:

[0x00007d84]0008:

00007d84（unk.ctxt）:

calleax

Andthefirstinstructionofkernelis:

[0x0010000c]0008:

0010000c（unk.ctxt）:

movwordptrds:

0x472,0x1234

Howdoesthebootloaderdecidehowmanysectorsitmustreadinordertofetchtheentirekernelfromdisk?

Wheredoesitfindthisinformation?

Thefunctionreadseg（ph->p_va,ph->p_memsz,ph->p_offset）;'ssecondparametertellthebootloaderhowmanysectorsshuoldbeload.

TheSECTSIZEis512defineinthemacro.

Exercise5

FamiliarwithClanguage

Youcandisplayafulllistofthenames,sizes,andlinkaddressesofallthesectionsinthekernelexecutablebytyping:

objdump-h********/lab1/obj/kernel/kernel

notthecommand:

i386-jos-elf-objdump-hobj/kern/kernel

Youcanseetheentrypointbytypethecommand:

objdump-f********/lab1/obj/kernel/kernel

notthecommand:

i386-jos-elf-objdump-fobj/kern/kernel

Wecanseethestartadressis0xf010000c,not0x0010000c,Why?

Exercise6

ThebootloaderloadtheElfto0x10000（fourzero）,itinitializethestructsofElf.h.

Whyaretheydifferent?

Becausethebootloadermovethedatato0c00100000（fivezero,ThestructsofElf.hincludethisvalue）usingthecodeinmain.c:

ph=（structProghdr*）（（uint8_t*）ELFHDR+ELFHDR->e_phoff）;

eph=ph+ELFHDR->e_phnum;

for（;ph

readseg（ph->p_va,ph->p_memsz,ph->p_offset）;

Thereis

0x00100000:

0x1badb0020x000000030xe4524ffb0x7205c766

0x00100010:

0x340000040x15010f120x0010f0180x000010b8

atthesecondbreakpoint.

Theyareexecutableinstructionsforkernel.

Butwhy0xf0000000==0x00000000

JusttypehelpinourJOS,wewillknowtheture.

_startf010000c（virt）0010000c（phys）（Theloadaddressandthelinkaddress）Whydon'tyoutellmefirst!

!

!

!

!

Exercise7

Ifichangethe"0x7c00"to"0x8c00"inboot/makefrag,thebochswillrunthebiosprogrammetoinitializetheidtandthedevices.

Butwhenfinishedinitialization,thenjumpto0x7c00continuetoruntheinstructions,thebochswillrestartthesimulator.

Why?

Becausethebootloaderisloadat0x8c00.Thereisnoinstructionsat0x7c00.

^^^^^^^^^^^^^^^^^^^^^^^^^PART3^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Exercise8

Restartbochs,Weshouldsetthebreakpointin0x0010000c（b0x0010000c）,andthentypec.

NowwetypestoseetheJOS'kernelrunstepbystep.

Iamsoluckthatiseetheinstrctionlgdtin[0x00100015]0008:

00100015.

SowecananswertheproblemofExercise8.

After[0x00100015]0008:

00100015thenewmappingtakeseffect.（segmentation,page?

weshouldseethecrregistorstojudgeit）.

Openthefileentry.Sthatinthefolderkern.

Wecommentout（注释）theinstruction"lgdtRELOC（mygdtdesc）"using#.

Andthensaveit.

Andthengotothefolderlab1typethecomment:

make

Thenwerunthebochsandsetthebreakpointat0x00100000c

andtypec,thentypes,s,s,.....

Wecanseethat

（0）[0x00100020]0008:

00100020（unk.ctxt）:

jmpfar0008:

f0100027;ea270010f00800

8>s

Nextatt=274078546

bx_dbg_read_linear:

physicalmemoryreaderror（phy=0xf0100027,lin=0xf0100027）

9>s

bx_dbg_read_linear:

physicalmemoryreaderror（phy=0xf0100027,lin=0xf0100027）

Why?

Becuasethenewgdtisn'tloadedtothegdtr.

当进入保护模式之后，段寄存器的值都变成索引值通过gdt转换的。

Andthenthe0x0008indexthesegmentdescriptorisn'tthethesegmentdescriptorwereallyneed.

Sothevirtualaddresstophysicaladdresschangeiserror（itchangetotheoldaddress）,Sotheresultaboveappear.

Nowwerestoretheentry.S.

AndmaketheJOSagain.

ToseethesourceofJOS'kernel,weneedtoinstallsomesoftwarelikesourceInsight,butinlinuxweusevim+cscopeinsteadofit.

1NowweneedtobuildtheindexinctagslikeSourceInsight.（Theteachersaysthatsourceinsightsimulatethectags,butnowiusectagstosimulatethesourceInsight,haha!

hehe!

:

-））

Gothetherootcatalogueoflab1,andthentypethecommand:

ctags-R

Thentheindexisestablished.Butwewilluseitlater.

Exercise9

Therelationshipamonginprintfmt.c,printf.candconsole.cis:

printfmt->vprintfmt->putch->cputchar->cons-putc->lpt-putc,cga-putc（setthecharcolor）

（printfmt.c..........）（printf.c）（console.c................................）

Thefillinthefunction"vprintfmt"is:

case'o':

//Replacethiswithyourcode.

//putch（'X',putdat）;

//putch（'X',putdat）;

//putch（'X',putdat）;

num=getuint（&ap,lflag）;

base=8;

gotonumber;

//break;

Thespecificationofconsole.c

question1:

lpt_putc（）usinginI/Oprarallelportpragraming

cag_putc（）setthecharandchar'colourthatdisplayonthescreen.15-8bitsaretheattributeofthechar,8-0bitsarethechar'sasciicode.

cons_putc（）printthecharonthescreenusethefuntionabove.

cputchar（）callthefunctioncons_putc（）

cprintf->vcprintf->vprintfmt->putch->cputchar->cons-putc->lpt-putc,cga-putc（setthecharcolor