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Subject: The Kernel Boot Process - Gustavo Duarte
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<header>
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<h1 class=3D"entry-title">The Kernel Boot Process</h1>
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<p class=3D"meta">
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<time datetime=3D"2008-06-23T02:20:17-06:00" pubdate=3D"" data-updated=3D"t=
rue">Jun 23<span>rd</span>, 2008</time>
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</p>
=20
</header>
<div class=3D"entry-content"><p> The previous post explained <a href=3D"htt=
ps://web.archive.org/web/20151004202005/http://duartes.org/gustavo/blog/pos=
t/how-computers-boot-up" _pageexpand_=3D"64">how computers boot up</a> righ=
t up to the point where the boot loader, after stuffing the kernel image in=
to memory, is about to jump into the kernel entry point. This last post ab=
out booting takes a look at the guts of the kernel to see how an operating =
system starts life. Since I have an <a href=3D"https://web.archive.org/web/=
20151004202005/http://duartes.org/gustavo/blog/post/reality-driven-developm=
ent" _pageexpand_=3D"68">empirical bent</a> I=E2=80=99ll link heavily to th=
e sources for Linux kernel 2.6.25.6 at the <a href=3D"https://web.archive.o=
rg/web/20151004202005/http://lxr.linux.no/" _pageexpand_=3D"72">Linux Cross=
Reference</a>. The sources are very readable if you are familiar with C-li=
ke syntax; even if you miss some details you can get the gist of what=E2=80=
=99s happening. The main obstacle is the lack of context around some of th=
e code, such as when or why it runs or the underlying features of the mach=
ine. I hope to provide a bit of that context. Due to brevity (hah!) a lot o=
f fun stuff - like interrupts and memory - gets only a nod for now. The po=
st ends with the highlights for the Windows boot. </p>
<p> </p><p> At this point in the Intel x86 boot story the processor is run=
ning in real-mode, is able to address 1 MB of memory, and RAM looks like th=
is for a modern Linux system: </p> <p align=3D"center"> <img alt=3D"RAM =
contents after boot loader runs" src=3D"https://web.archive.org/web/2015100=
4202005im_/http://static.duartes.org/img/blogPosts/memoryAfterBootloader.pn=
g" _pageexpand_=3D"76"> <font size=3D"-1"><br>RAM contents after boot loa=
der is done</font> </p> <p> The kernel image has been loaded to memory by =
the boot loader using the BIOS disk I/O services. This image is an exact co=
py of the file in your hard drive that contains the kernel, e.g. <b>/boot/v=
mlinuz-2.6.22-14-server</b>. The image is split into two pieces: a small pa=
rt containing the real-mode kernel code is loaded below the 640K barrier; t=
he bulk of the kernel, which runs in protected mode, is loaded after the fi=
rst megabyte of memory. </p> <p> The action starts in the real-mode kernel=
header pictured above. This region of memory is used to implement the <a h=
ref=3D"https://web.archive.org/web/20151004202005/http://lxr.linux.no/linux=
+v2.6.25.6/Documentation/i386/boot.txt" _pageexpand_=3D"80"> Linux boot p=
rotocol</a> between the boot loader and the kernel. Some of the values ther=
e are read by the boot loader while doing its work. These include amenities=
such as a human-readable string containing the kernel version, but also cr=
ucial information like the size of the real-mode kernel piece. The boot loa=
der also <i>writes</i> values to this region, such as the memory address fo=
r the command-line parameters given by the user in the boot menu. Once the =
boot loader is finished it has filled in all of the parameters required by =
the kernel header. It=E2=80=99s then time to jump into the kernel entry poi=
nt. The diagram below shows the code sequence for the kernel initialization=
, along with source directories, files, and line numbers: </p> <p align=3D=
"center"> <img alt=3D"Architecture-specific Linux Kernel Initialization" =
src=3D"https://web.archive.org/web/20151004202005im_/http://static.duartes.=
org/img/blogPosts/kernelInitPartOne.png" _pageexpand_=3D"84"> <font siz=
e=3D"-1"><br>Architecture-specific Linux Kernel Initialization</font> </p> =
<p> The early kernel start-up for the Intel architecture is in file <a hr=
ef=3D"https://web.archive.org/web/20151004202005/http://lxr.linux.no/linux+=
v2.6.25.6/arch/x86/boot/header.S" _pageexpand_=3D"88">arch/x86/boot/header.=
S</a>. It=E2=80=99s in assembly language, which is rare for the kernel at l=
arge but common for boot code. The start of this file actually contains boo=
t sector code, a left over from the days when Linux could work without a bo=
ot loader. Nowadays this boot sector, if executed, only prints a =E2=80=9Cb=
ugger_off_msg=E2=80=9D to the user and reboots. Modern boot loaders ignore =
this legacy code. After the boot sector code we have the first 15 bytes of =
the real-mode kernel header; these two pieces together add up to 512 bytes,=
the size of a typical disk sector on Intel hardware.</p> <p> After these =
512 bytes, at offset 0x200, we find the very first instruction that runs a=
s part of the Linux kernel: the real-mode entry point. It=E2=80=99s in <a =
href=3D"https://web.archive.org/web/20151004202005/http://lxr.linux.no/linu=
x+v2.6.25.6/arch/x86/boot/header.S#L110" _pageexpand_=3D"92">header.S:110</=
a> and it is a 2-byte jump written directly in machine code as 0x3aeb. You=
can verify this by running hexdump on your kernel image and seeing the byt=
es at that offset =E2=80=93 just a sanity check to make sure it=E2=80=99s n=
ot all a dream. The boot loader jumps into this location when it is finishe=
d, which in turn jumps to <a href=3D"https://web.archive.org/web/201510042=
02005/http://lxr.linux.no/linux+v2.6.25.6/arch/x86/boot/header.S#L229" _pag=
eexpand_=3D"96">header.S:229</a> where we have a regular assembly routine c=
alled start_of_setup. This short routine sets up a stack, zeroes the <a hre=
f=3D"https://web.archive.org/web/20151004202005/http://en.wikipedia.org/wik=
i/.bss" _pageexpand_=3D"100">bss</a> segment (the area that contains stati=
c variables, so they start with zero values) for the real-mode kernel and t=
hen jumps to good old C code at <a href=3D"https://web.archive.org/web/201=
51004202005/http://lxr.linux.no/linux+v2.6.25.6/arch/x86/boot/main.c#L122" =
_pageexpand_=3D"104">arch/x86/boot/main.c:122</a>. </p> <p> main() does so=
me house keeping like detecting memory layout, setting a video mode, etc. I=
t then calls <a href=3D"https://web.archive.org/web/20151004202005/http://=
lxr.linux.no/linux+v2.6.25.6/arch/x86/boot/pm.c#L153" _pageexpand_=3D"108">=
go_to_protected_mode()</a>. Before the CPU can be set to protected mode, ho=
wever, a few tasks must be done. There are two main issues: interrupts and =
memory. In real-mode the <a href=3D"https://web.archive.org/web/20151004202=
005/http://en.wikipedia.org/wiki/Interrupt_vector_table" _pageexpand_=3D"11=
2">interrupt vector table</a> for the processor is always at memory address=
0, whereas in protected mode the location of the interrupt vector table is=
stored in a CPU register called IDTR. Meanwhile, the translation of logic=
al memory addresses (the ones programs manipulate) to linear memory address=
es (a raw number from 0 to the top of the memory) is different between real=
-mode and protected mode. Protected mode requires a register called GDTR to=
be loaded with the address of a <a href=3D"https://web.archive.org/web/201=
51004202005/http://en.wikipedia.org/wiki/Global_descriptor_table" _pageexpa=
nd_=3D"116">Global Descriptor Table</a> for memory. So go_to_protected_mode=
() calls <a href=3D"https://web.archive.org/web/20151004202005/http://lxr.=
linux.no/linux+v2.6.25.6/arch/x86/boot/pm.c#L144" _pageexpand_=3D"120">setu=
p_idt()</a> and <a href=3D"https://web.archive.org/web/20151004202005/http=
://lxr.linux.no/linux+v2.6.25.6/arch/x86/boot/pm.c#L115" _pageexpand_=3D"12=
4">setup_gdt()</a> to install a temporary interrupt descriptor table and gl=
obal descriptor table.</p> <p> We=E2=80=99re now ready for the plunge into=
protected mode, which is done by <a href=3D"https://web.archive.org/web/20=
151004202005/http://lxr.linux.no/linux+v2.6.25.6/arch/x86/boot/pmjump.S#L31=
" _pageexpand_=3D"128">protected_mode_jump</a>, another assembly routine. =
This routine enables protected mode by setting the PE bit in the CR0 CPU r=
egister. At this point we=E2=80=99re running with <a href=3D"https://web.ar=
chive.org/web/20151004202005/http://en.wikipedia.org/wiki/Paging" _pageexpa=
nd_=3D"132">paging</a> <b>disabled</b>; paging is an optional feature of th=
e processor, even in protected mode, and there=E2=80=99s no need for it yet=
. What=E2=80=99s important is that we=E2=80=99re no longer confined to the =
640K barrier and can now address up to 4GB of RAM. The routine then calls t=
he 32-bit kernel entry point, which is <a href=3D"https://web.archive.org=
/web/20151004202005/http://lxr.linux.no/linux+v2.6.25.6/arch/x86/boot/compr=
essed/head_32.S#L35" _pageexpand_=3D"136">startup_32</a> for compressed ke=
rnels. This routine does some basic register initializations and calls <=
a href=3D"https://web.archive.org/web/20151004202005/http://lxr.linux.no/li=
nux+v2.6.25.6/arch/x86/boot/compressed/misc.c#L368" _pageexpand_=3D"140">de=
compress_kernel()</a>, a C function to do the actual decompression. </p><=
p>decompress_kernel() prints the familiar =E2=80=9CDecompressing Linux=E2=
=80=A6=E2=80=9D message. Decompression happens in-place and once it=E2=80=
=99s finished the uncompressed kernel image has overwritten the compressed=
one pictured in the first diagram. Hence the uncompressed contents also st=
art at 1MB. decompress_kernel() then prints =E2=80=9Cdone.=E2=80=9D and the=
comforting =E2=80=9CBooting the kernel.=E2=80=9D By =E2=80=9CBooting=E2=
=80=9D it means a jump to the final entry point in this whole story, given=
to Linus by God himself atop <a href=3D"https://web.archive.org/web/201510=
04202005/http://en.wikipedia.org/wiki/Halti" _pageexpand_=3D"144">Mountain =
Halti</a>, which is the protected-mode kernel entry point at the start of t=
he second megabyte of RAM (0x100000). That sacred location contains a rout=
ine called, uh, <a href=3D"https://web.archive.org/web/20151004202005/http:=
//lxr.linux.no/linux+v2.6.25.6/arch/x86/kernel/head_32.S#L86" _pageexpand_=
=3D"148">startup_32</a>. But <i>this</i> one is in a different directory, y=
ou see. </p> <p> The second incarnation of startup_32 is also an assembly=
routine, but it contains 32-bit mode initializations. It clears the bss se=
gment for the protected-mode kernel (which is the <i>true</i> kernel that w=
ill now run until the machine reboots or shuts down), sets up the final glo=
bal descriptor table for memory, builds page tables so that paging can be t=
urned on, enables paging, initializes a stack, creates the final interrupt=
descriptor table, and finally jumps to to the architecture-independent ke=
rnel start-up, <a href=3D"https://web.archive.org/web/20151004202005/http:=
//lxr.linux.no/linux+v2.6.25.6/init/main.c#L507" _pageexpand_=3D"152">start=
_kernel()</a>. The diagram below shows the code flow for the last leg of th=
e boot: </p> <p align=3D"center"> <img alt=3D"Architecture-independent=
Linux Kernel Initialization" src=3D"https://web.archive.org/web/2015100420=
2005im_/http://static.duartes.org/img/blogPosts/kernelInitPartTwo.png" _pag=
eexpand_=3D"156"> <font size=3D"-1"><br>Architecture-independent Linux Ker=
nel Initialization</font> </p> <p> start_kernel() looks more like typical =
kernel code, which is nearly all C and machine independent. The function is=
a long list of calls to initializations of the various kernel subsystems a=
nd data structures. These include the scheduler, memory zones, time keeping=
, and so on. start_kernel() then calls <a href=3D"https://web.archive.org/=
web/20151004202005/http://lxr.linux.no/linux+v2.6.25.6/init/main.c#L432" _p=
ageexpand_=3D"160">rest_init()</a>, at which point things are almost all wo=
rking. rest_init() creates a kernel thread passing another function, <a hre=
f=3D"https://web.archive.org/web/20151004202005/http://lxr.linux.no/linux+v=
2.6.25.6/init/main.c#L808" _pageexpand_=3D"164">kernel_init()</a>, as the e=
ntry point. rest_init() then calls <a href=3D"https://web.archive.org/web/2=
0151004202005/http://lxr.linux.no/linux+v2.6.25.6/kernel/sched.c#L3959" _pa=
geexpand_=3D"168">schedule()</a> to kickstart task scheduling and goes to =
sleep by calling <a href=3D"https://web.archive.org/web/20151004202005/htt=
p://lxr.linux.no/linux+v2.6.25.6/arch/x86/kernel/process_32.c#L180" _pageex=
pand_=3D"172">cpu_idle()</a>, which is the idle thread for the Linux kernel=
. cpu_idle() runs forever and so does process zero, which hosts it. Wheneve=
r there is work to do =E2=80=93 a runnable process =E2=80=93 process zero g=
ets booted out of the CPU, only to return when no runnable processes are av=
ailable. </p> <p> But here=E2=80=99s the kicker for us. This idle loop is =
the end of the long thread we followed since boot, it=E2=80=99s the final d=
escendent of the very first <i>jump</i> executed by the processor after pow=
er up. All of this mess, from reset vector to BIOS to MBR to boot loader to=
real-mode kernel to protected-mode kernel, all of it leads right here, ju=
mp by jump by jump it ends in the idle loop for the boot processor, cpu_idl=
e(). Which is really kind of cool. However, this can=E2=80=99t be the whol=
e story otherwise the computer would do no work. </p> <p> At this point, t=
he kernel thread started previously is ready to kick in, displacing process=
0 and its idle thread. And so it does, at which point kernel_init() start=
s running since it was given as the thread entry point. <a href=3D"https:/=
/web.archive.org/web/20151004202005/http://lxr.linux.no/linux+v2.6.25.6/ini=
t/main.c#L808" _pageexpand_=3D"176">kernel_init()</a> is responsible for in=
itializing the remaining CPUs in the system, which have been halted since b=
oot. All of the code we=E2=80=99ve seen so far has been executed in a singl=
e CPU, called the boot processor. As the other CPUs, called application pro=
cessors, are started they come up in real-mode and must run through several=
initializations as well. Many of the code paths are common, as you can see=
in the code for <a href=3D"https://web.archive.org/web/20151004202005/http=
://lxr.linux.no/linux+v2.6.25.6/arch/x86/kernel/head_32.S#L86" _pageexpand_=
=3D"180">startup_32</a>, but there are slight forks taken by the late-comin=
g application processors. Finally, kernel_init() calls <a href=3D"https:/=
/web.archive.org/web/20151004202005/http://lxr.linux.no/linux+v2.6.25.6/ini=
t/main.c#L769" _pageexpand_=3D"184">init_post()</a>, which tries to execut=
e a user-mode process in the following order: /sbin/init, /etc/init, /bin/i=
nit, and /bin/sh. If all fail, the kernel will panic. Luckily init is usual=
ly there, and starts running as PID 1. It checks its configuration file to=
figure out which processes to launch, which might include X11 Windows, pro=
grams for logging in on the console, network daemons, and so on. Thus ends =
the boot process as yet another Linux box starts running somewhere. May you=
r uptime be long and untroubled. </p> <p> The process for Windows is simil=
ar in many ways, given the common architecture. Many of the same problems =
are faced and similar initializations must be done. When it comes to boot o=
ne of the biggest differences is that Windows packs all of the real-mode ke=
rnel code, and some of the initial protected mode code, into the boot loade=
r itself (C:\NTLDR). So instead of having two regions in the same kernel im=
age, Windows uses different binary images. Plus Linux completely separates =
boot loader and kernel; in a way this automatically falls out of the open s=
ource process. The diagram below shows the main bits for the Windows kernel=
: </p><p> </p><p align=3D"center"> <img alt=3D"Windows Kernel Initiali=
zation" src=3D"https://web.archive.org/web/20151004202005im_/http://static.=
duartes.org/img/blogPosts/windowsKernelInit.png" _pageexpand_=3D"188"> =
<font size=3D"-1"><br>Windows Kernel Initialization</font> </p> <p> The Wi=
ndows user-mode start-up is naturally very different. There=E2=80=99s no /s=
bin/init, but rather Csrss.exe and Winlogon.exe. Winlogon spawns <b>Servic=
es.exe</b>, which starts all of the Windows Services, and Lsass.exe, the lo=
cal security authentication subsystem. The classic Windows login dialog run=
s in the context of Winlogon. </p> <p> This is the end of this boot series=
. Thanks everyone for reading and for feedback. I=E2=80=99m sorry some thin=
gs got superficial treatment; I=E2=80=99ve gotta start somewhere and only s=
o much fits into blog-sized bites. But nothing like a day after the next; m=
y plan is to do regular =E2=80=9CSoftware Illustrated=E2=80=9D posts like t=
his series along with other topics. Meanwhile, here are some resources: </p=
> <ul> <li>The best, most important resource, is source code for real ker=
nels, either Linux or one of the BSDs.</li> <li>Intel publishes excellent=
<a href=3D"https://web.archive.org/web/20151004202005/http://www.intel.c=
om/products/processor/manuals/index.htm" _pageexpand_=3D"224">Software Deve=
loper=E2=80=99s Manuals</a>, which you can download for free.</li> =
<li><a href=3D"https://web.archive.org/web/20151004202005/http://www.amazon=
.com/exec/obidos/ASIN/0596005652/gustduar-20" _pageexpand_=3D"228">Understa=
nding the Linux Kernel</a> is a good book and walks through a lot of the Li=
nux Kernel sources. It=E2=80=99s getting outdated and it=E2=80=99s dry, b=
ut I=E2=80=99d still recommend it to anyone who wants to grok the kernel. =
<a href=3D"https://web.archive.org/web/20151004202005/http://www.amazon.=
com/exec/obidos/ASIN/0596005903/gustduar-20" _pageexpand_=3D"232">Linux Dev=
ice Drivers</a> is more fun, teaches well, but is limited in scope. Finally=
, Patrick Moroney suggested <a href=3D"https://web.archive.org/web/20151004=
202005/http://www.amazon.com/exec/obidos/ASIN/0672327201/gustduar-20" _page=
expand_=3D"236">Linux Kernel Development</a> by Robert Love in the comments=
for this post. I=E2=80=99ve heard other positive reviews for that book, so=
it sounds worth checking out. </li> <li>For Windows, the best ref=
erence by far is <a href=3D"https://web.archive.org/web/20151004202005/ht=
tp://www.amazon.com/exec/obidos/ASIN/0735625301/gustduar-20" _pageexpand_=
=3D"240">Windows Internals</a> by David Solomon and <a href=3D"https://web=
.archive.org/web/20151004202005/http://blogs.technet.com/markrussinovich/" =
_pageexpand_=3D"244">Mark Russinovich</a>, the latter of Sysinternals fame.=
This is a great book, well-written and thorough. The main downside is=
the lack of source code. </li> </ul><p></p>
<p>[Update: In a <a href=3D"https://web.archive.org/web/20151004202005/http=
://duartes.org/gustavo/blog/post/kernel-boot-process/#comment-13790" _pagee=
xpand_=3D"192">comment below</a>, Nix covered a lot of ground on the initia=
l root file system that I glossed over. Thanks to <a href=3D"https://web.ar=
chive.org/web/20151004202005/http://www.sirartisan.net/" _pageexpand_=3D"19=
6">Marius Barbu</a> for catching a mistake where I wrote =E2=80=9CCR3=E2=80=
=9D instead of GDTR]</p>
<p><a href=3D"https://web.archive.org/web/20151004202005/http://duartes.org=
/gustavo/blog/comments/kernel-boot.html" _pageexpand_=3D"200">104 Comments<=
/a></p>
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ss/#ar" _pageexpand_=3D"376">Arabic</a></td><td><a tabindex=3D"-1" href=3D"=
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bindex=3D"-1" href=3D"https://web.archive.org/web/20151004202005/http://dua=
rtes.org/gustavo/blog/post/kernel-boot-process/#pl" _pageexpand_=3D"384">Po=
lish</a></td> </tr><tr> <td><a tabindex=3D"-1" href=3D"https://web.archive.=
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cess/#bg" _pageexpand_=3D"388">Bulgarian</a></td><td><a tabindex=3D"-1" hre=
f=3D"https://web.archive.org/web/20151004202005/http://duartes.org/gustavo/=
blog/post/kernel-boot-process/#hi" _pageexpand_=3D"392">Hindi</a></td><td><=
a tabindex=3D"-1" href=3D"https://web.archive.org/web/20151004202005/http:/=
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archive.org/web/20151004202005/http://duartes.org/gustavo/blog/post/kernel-=
boot-process/#ca" _pageexpand_=3D"400">Catalan</a></td><td><a tabindex=3D"-=
1" href=3D"https://web.archive.org/web/20151004202005/http://duartes.org/gu=
stavo/blog/post/kernel-boot-process/#mww" _pageexpand_=3D"404">Hmong Daw</a=
></td><td><a tabindex=3D"-1" href=3D"https://web.archive.org/web/2015100420=
2005/http://duartes.org/gustavo/blog/post/kernel-boot-process/#ro" _pageexp=
and_=3D"408">Romanian</a></td> </tr><tr> <td><a tabindex=3D"-1" href=3D"htt=
ps://web.archive.org/web/20151004202005/http://duartes.org/gustavo/blog/pos=
t/kernel-boot-process/#zh-CHS" _pageexpand_=3D"412">Chinese Simplified</a><=
/td><td><a tabindex=3D"-1" href=3D"https://web.archive.org/web/201510042020=
05/http://duartes.org/gustavo/blog/post/kernel-boot-process/#hu" _pageexpan=
d_=3D"416">Hungarian</a></td><td><a tabindex=3D"-1" href=3D"https://web.arc=
hive.org/web/20151004202005/http://duartes.org/gustavo/blog/post/kernel-boo=
t-process/#ru" _pageexpand_=3D"420">Russian</a></td> </tr><tr> <td><a tabin=
dex=3D"-1" href=3D"https://web.archive.org/web/20151004202005/http://duarte=
s.org/gustavo/blog/post/kernel-boot-process/#zh-CHT" _pageexpand_=3D"424">C=
hinese Traditional</a></td><td><a tabindex=3D"-1" href=3D"https://web.archi=
ve.org/web/20151004202005/http://duartes.org/gustavo/blog/post/kernel-boot-=
process/#id" _pageexpand_=3D"428">Indonesian</a></td><td><a tabindex=3D"-1"=
href=3D"https://web.archive.org/web/20151004202005/http://duartes.org/gust=
avo/blog/post/kernel-boot-process/#sk" _pageexpand_=3D"432">Slovak</a></td>=
</tr><tr> <td><a tabindex=3D"-1" href=3D"https://web.archive.org/web/20151=
004202005/http://duartes.org/gustavo/blog/post/kernel-boot-process/#cs" _pa=
geexpand_=3D"436">Czech</a></td><td><a tabindex=3D"-1" href=3D"https://web.=
archive.org/web/20151004202005/http://duartes.org/gustavo/blog/post/kernel-=
boot-process/#it" _pageexpand_=3D"440">Italian</a></td><td><a tabindex=3D"-=
1" href=3D"https://web.archive.org/web/20151004202005/http://duartes.org/gu=
stavo/blog/post/kernel-boot-process/#sl" _pageexpand_=3D"444">Slovenian</a>=
</td> </tr><tr> <td><a tabindex=3D"-1" href=3D"https://web.archive.org/web/=
20151004202005/http://duartes.org/gustavo/blog/post/kernel-boot-process/#da=
" _pageexpand_=3D"448">Danish</a></td><td><a tabindex=3D"-1" href=3D"https:=
//web.archive.org/web/20151004202005/http://duartes.org/gustavo/blog/post/k=
ernel-boot-process/#ja" _pageexpand_=3D"452">Japanese</a></td><td><a tabind=
ex=3D"-1" href=3D"https://web.archive.org/web/20151004202005/http://duartes=
.org/gustavo/blog/post/kernel-boot-process/#es" _pageexpand_=3D"456">Spanis=
h</a></td> </tr><tr> <td><a tabindex=3D"-1" href=3D"https://web.archive.org=
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s/#nl" _pageexpand_=3D"460">Dutch</a></td><td><a tabindex=3D"-1" href=3D"ht=
tps://web.archive.org/web/20151004202005/http://duartes.org/gustavo/blog/po=
st/kernel-boot-process/#tlh" _pageexpand_=3D"464">Klingon</a></td><td><a ta=
bindex=3D"-1" href=3D"https://web.archive.org/web/20151004202005/http://dua=
rtes.org/gustavo/blog/post/kernel-boot-process/#sv" _pageexpand_=3D"468">Sw=
edish</a></td> </tr><tr> <td><a tabindex=3D"-1" href=3D"https://web.archive=
.org/web/20151004202005/http://duartes.org/gustavo/blog/post/kernel-boot-pr=
ocess/#en" _pageexpand_=3D"472">English</a></td><td><a tabindex=3D"-1" href=
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log/post/kernel-boot-process/#ko" _pageexpand_=3D"476">Korean</a></td><td><=
a tabindex=3D"-1" href=3D"https://web.archive.org/web/20151004202005/http:/=
/duartes.org/gustavo/blog/post/kernel-boot-process/#th" _pageexpand_=3D"480=
">Thai</a></td> </tr><tr> <td><a tabindex=3D"-1" href=3D"https://web.archiv=
e.org/web/20151004202005/http://duartes.org/gustavo/blog/post/kernel-boot-p=
rocess/#et" _pageexpand_=3D"484">Estonian</a></td><td><a tabindex=3D"-1" hr=
ef=3D"https://web.archive.org/web/20151004202005/http://duartes.org/gustavo=
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d><a tabindex=3D"-1" href=3D"https://web.archive.org/web/20151004202005/htt=
p://duartes.org/gustavo/blog/post/kernel-boot-process/#tr" _pageexpand_=3D"=
492">Turkish</a></td> </tr><tr> <td><a tabindex=3D"-1" href=3D"https://web.=
archive.org/web/20151004202005/http://duartes.org/gustavo/blog/post/kernel-=
boot-process/#fi" _pageexpand_=3D"496">Finnish</a></td><td><a tabindex=3D"-=
1" href=3D"https://web.archive.org/web/20151004202005/http://duartes.org/gu=
stavo/blog/post/kernel-boot-process/#lt" _pageexpand_=3D"500">Lithuanian</a=
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2005/http://duartes.org/gustavo/blog/post/kernel-boot-process/#uk" _pageexp=
and_=3D"504">Ukrainian</a></td> </tr><tr> <td><a tabindex=3D"-1" href=3D"ht=
tps://web.archive.org/web/20151004202005/http://duartes.org/gustavo/blog/po=
st/kernel-boot-process/#fr" _pageexpand_=3D"508">French</a></td><td><a tabi=
ndex=3D"-1" href=3D"https://web.archive.org/web/20151004202005/http://duart=
es.org/gustavo/blog/post/kernel-boot-process/#ms" _pageexpand_=3D"512">Mala=
y</a></td><td><a tabindex=3D"-1" href=3D"https://web.archive.org/web/201510=
04202005/http://duartes.org/gustavo/blog/post/kernel-boot-process/#ur" _pag=
eexpand_=3D"516">Urdu</a></td> </tr><tr> <td><a tabindex=3D"-1" href=3D"htt=
ps://web.archive.org/web/20151004202005/http://duartes.org/gustavo/blog/pos=
t/kernel-boot-process/#de" _pageexpand_=3D"520">German</a></td><td><a tabin=
dex=3D"-1" href=3D"https://web.archive.org/web/20151004202005/http://duarte=
s.org/gustavo/blog/post/kernel-boot-process/#mt" _pageexpand_=3D"524">Malte=
se</a></td><td><a tabindex=3D"-1" href=3D"https://web.archive.org/web/20151=
004202005/http://duartes.org/gustavo/blog/post/kernel-boot-process/#vi" _pa=
geexpand_=3D"528">Vietnamese</a></td> </tr><tr> <td><a tabindex=3D"-1" href=
=3D"https://web.archive.org/web/20151004202005/http://duartes.org/gustavo/b=
log/post/kernel-boot-process/#el" _pageexpand_=3D"532">Greek</a></td><td><a=