jmp main-0x7c00+0x600	# Jump to relocated code</programlisting>

      jmp main-0x7c00+0x600	# Jump to relocated code</programlisting>

    </figure>

    </figure>

      <acronym>BIOS</acronym> to address <literal>0x7C00</literal>, it

      <acronym>BIOS</acronym> to address <literal>0x7C00</literal>, it

      copies itself to address <literal>0x600</literal> and then

      copies itself to address <literal>0x600</literal> and then

      transfers control there (recall that it was linked to execute at

      transfers control there (recall that it was linked to execute at

      bytes of <filename>boot</filename> and, because

      bytes of <filename>boot</filename> and, because

      <filename>boot</filename> is written to the first sector of the

      <filename>boot</filename> is written to the first sector of the

      &os; slice, <filename>boot1</filename> fits exactly in this

      &os; slice, <filename>boot1</filename> fits exactly in this

      16 sectors of the &os; slice, it effectively reads the entire

      16 sectors of the &os; slice, it effectively reads the entire

      <filename>boot</filename> file

      <filename>boot</filename> file

      <footnote>

      <footnote>

      flags in the EFLAGS register.  Note that the

      flags in the EFLAGS register.  Note that the

      <literal>popfl</literal> instruction pops out a doubleword (4

      <literal>popfl</literal> instruction pops out a doubleword (4

      bytes) from the stack and places it in the EFLAGS register.

      bytes) from the stack and places it in the EFLAGS register.

      EFLAGS register is effectively cleared (IA-32 requires that bit

      EFLAGS register is effectively cleared (IA-32 requires that bit

      2 of the EFLAGS register always be 1).</para>

      2 of the EFLAGS register always be 1).</para>

      abstraction.  The IA-32 architecture demands the creation and

      abstraction.  The IA-32 architecture demands the creation and

      use of <emphasis>at least</emphasis> one <acronym>TSS</acronym>

      use of <emphasis>at least</emphasis> one <acronym>TSS</acronym>

      if multitasking facilities are used or different privilege

      if multitasking facilities are used or different privilege

      client is executed in privilege level 3, but the

      client is executed in privilege level 3, but the

      <acronym>BTX</acronym> server does in privilege level 0, a

      <acronym>BTX</acronym> server does in privilege level 0, a

      <acronym>TSS</acronym> must be defined:</para>

      <acronym>TSS</acronym> must be defined:</para>

    <para>For this reason, no serious applications rely on block

    <para>For this reason, no serious applications rely on block

      devices, and in fact, almost all applications which access

      devices, and in fact, almost all applications which access

      disks directly take great pains to specify that character

      disks directly take great pains to specify that character

      the implementation of the aliasing of each disk (partition) to

      the implementation of the aliasing of each disk (partition) to

      two devices with different semantics significantly complicated

      two devices with different semantics significantly complicated

      devices as part of the modernization of the disk I/O

      devices as part of the modernization of the disk I/O

      infrastructure.</para>

      infrastructure.</para>

  </sect1>

  </sect1>

        with PnP. This feature is not implemented in any existing

        with PnP. This feature is not implemented in any existing

        driver and is not considered further in this document.</para>

        driver and is not considered further in this document.</para>

        legacy devices they will not be attached twice (once as legacy

        legacy devices they will not be attached twice (once as legacy

        and once as PnP).  But in case of device-dependent identify

        and once as PnP).  But in case of device-dependent identify

        routines it is the responsibility of the driver to make sure

        routines it is the responsibility of the driver to make sure

              Free the memory allocated by

              Free the memory allocated by

              <function>bus_dmamem_alloc()</function>. At present,

              <function>bus_dmamem_alloc()</function>. At present,

              freeing of the memory allocated with ISA restrictions is

              freeing of the memory allocated with ISA restrictions is

              of use is to keep and re-use the allocated areas for as

              of use is to keep and re-use the allocated areas for as

              long as possible. Do not lightly free some area and then

              long as possible. Do not lightly free some area and then

              shortly allocate it again. That does not mean that

              shortly allocate it again. That does not mean that

          Before calling the callback function from

          Before calling the callback function from

          <function>bus_dmamap_load()</function> the segment array is

          <function>bus_dmamap_load()</function> the segment array is

          stored in the stack. And it gets pre-allocated for the

          stored in the stack. And it gets pre-allocated for the

          this the practical limit for the number of segments on i386

          this the practical limit for the number of segments on i386

          architecture is about 250-300 (the kernel stack is 4KB minus

          architecture is about 250-300 (the kernel stack is 4KB minus

          the size of the user structure, size of a segment array

          the size of the user structure, size of a segment array

          array is allocated based on the maximal number this value

          array is allocated based on the maximal number this value

          must not be set higher than really needed. Fortunately, for

          must not be set higher than really needed. Fortunately, for

          most of hardware the maximal supported number of segments is

          most of hardware the maximal supported number of segments is

          int error = 0;</programlisting>

          int error = 0;</programlisting>

        <para>Then allocate and activate all the necessary

        <para>Then allocate and activate all the necessary

          before returning from probe, it has to be allocated

          before returning from probe, it has to be allocated

          again. We expect that the probe routine had properly set all

          again. We expect that the probe routine had properly set all

          the resource ranges, as well as saved them in the structure

          the resource ranges, as well as saved them in the structure

      <indexterm><primary>Linksys</primary></indexterm>

      <indexterm><primary>Linksys</primary></indexterm>

      <indexterm><primary>D-Link</primary></indexterm>

      <indexterm><primary>D-Link</primary></indexterm>

	numeric IDs for device identification.  Using numeric IDs and

	numeric IDs for device identification.  Using numeric IDs and

	a centralized database complicates adding IDs and support for

	a centralized database complicates adding IDs and support for

	cards to the system.  One must carefully check to see who

	cards to the system.  One must carefully check to see who

      then also converting the SCSI commands to the native commands of

      then also converting the SCSI commands to the native commands of

      the hardware).</para>

      the hardware).</para>

      here, from this point on we will consider everything from the

      here, from this point on we will consider everything from the

      SIM standpoint.</para>

      SIM standpoint.</para>

	  the timeout to make sure that the target is not sleeping

	  the timeout to make sure that the target is not sleeping

	  forever.  If the command would not get aborted in some

	  forever.  If the command would not get aborted in some

	  reasonable time like 10 seconds the timeout routine would go

	  reasonable time like 10 seconds the timeout routine would go

	  will be aborted in some reasonable time we can just return

	  will be aborted in some reasonable time we can just return

	  the abort request now as successfully completed, and mark

	  the abort request now as successfully completed, and mark

	  the aborted CCB as aborted (but not mark it as done

	  the aborted CCB as aborted (but not mark it as done

    return;</programlisting>

    return;</programlisting>

	<para>That is all for the ABORT request, although there is one

	<para>That is all for the ABORT request, although there is one

	  ongoing transactions on a LUN we have to mark all the other

	  ongoing transactions on a LUN we have to mark all the other

	  active transactions on this LUN as aborted.  That should be

	  active transactions on this LUN as aborted.  That should be

	  done in the interrupt routine, after the transaction gets

	  done in the interrupt routine, after the transaction gets

      routine (or the other way around, the poll routine may be doing

      routine (or the other way around, the poll routine may be doing

      the real action and the interrupt routine would just call the

      the real action and the interrupt routine would just call the

      poll routine).  Why bother about a separate function then?

      poll routine).  Why bother about a separate function then?

      <function>xxx_poll</function> routine gets the struct cam_sim

      <function>xxx_poll</function> routine gets the struct cam_sim

      pointer as its argument when the PCI interrupt routine by common

      pointer as its argument when the PCI interrupt routine by common

      convention gets pointer to the struct

      convention gets pointer to the struct

    <para>Example: Firmware download Many devices that have been

    <para>Example: Firmware download Many devices that have been

      developed are based on a general purpose processor with an

      developed are based on a general purpose processor with an

      drivers and firmware for USB devices is still very new, many

      drivers and firmware for USB devices is still very new, many

      devices require the downloading of the firmware after they have

      devices require the downloading of the firmware after they have

      been connected.</para>

      been connected.</para>

	  packet processing code in the way BSD IPv4 code is

	  packet processing code in the way BSD IPv4 code is

	  implemented, kernel stack may overflow due to long function

	  implemented, kernel stack may overflow due to long function

	  call chain.  sys/netinet6 code is carefully designed to

	  call chain.  sys/netinet6 code is carefully designed to

	  code defines its own protocol switch structure, as "struct

	  code defines its own protocol switch structure, as "struct

	  ip6protosw" (see

	  ip6protosw" (see

	  <filename>netinet6/ip6protosw.h</filename>).  There is no

	  <filename>netinet6/ip6protosw.h</filename>).  There is no

	  such update to IPv4 part (sys/netinet) for compatibility,

	  such update to IPv4 part (sys/netinet) for compatibility,

	  but small change is added to its pr_input() prototype.  So

	  but small change is added to its pr_input() prototype.  So

	  receive IPsec-over-IPv4 packet with massive number of IPsec

	  receive IPsec-over-IPv4 packet with massive number of IPsec

	  headers, kernel stack may blow up.  IPsec-over-IPv6 is okay.

	  headers, kernel stack may blow up.  IPsec-over-IPv6 is okay.

	  (Off-course, for those all IPsec headers to be processed,

	  (Off-course, for those all IPsec headers to be processed,

	&man.dcons.4; provides similar functionality as a serial

	&man.dcons.4; provides similar functionality as a serial

	console.  It emulates two serial ports, one for the console

	console.  It emulates two serial ports, one for the console

	and <acronym>DDB</acronym>, the other for

	and <acronym>DDB</acronym>, the other for

	handled by the hardware, the &man.dcons.4; buffer is

	handled by the hardware, the &man.dcons.4; buffer is

	accessible even when the system crashes.</para>

	accessible even when the system crashes.</para>

      <indexterm><primary>seteuid</primary></indexterm>

      <indexterm><primary>seteuid</primary></indexterm>

      <para>There are at least 6 different IDs associated with any

      <para>There are at least 6 different IDs associated with any

      the access that your process has at any given time.  In

      the access that your process has at any given time.  In

      particular, all seteuid applications should give up their

      particular, all seteuid applications should give up their

      privileges as soon as it is no longer required.</para>

      privileges as soon as it is no longer required.</para>

      computer at speeds approaching the speed of light, it often

      computer at speeds approaching the speed of light, it often

      travels considerably slower between two computers.</para>

      travels considerably slower between two computers.</para>

      terse, we usually refer to them as

      terse, we usually refer to them as

      <emphasis>protocols</emphasis> rather than languages.</para>

      <emphasis>protocols</emphasis> rather than languages.</para>

      extract the <emphasis><acronym>PNG</acronym> file</emphasis>

      extract the <emphasis><acronym>PNG</acronym> file</emphasis>

      from it.</para>

      from it.</para>

      use the <function role="syscall">open</function> system call, or

      use the <function role="syscall">open</function> system call, or

      the <function>open()</function> C function.  Instead, we need to

      the <function>open()</function> C function.  Instead, we need to

      take several steps to <quote>opening</quote> a socket.</para>

      take several steps to <quote>opening</quote> a socket.</para>

	  <para>Not all protocols are that simple.  Many receive a

	  <para>Not all protocols are that simple.  Many receive a

	    request from the client, reply to it, then receive another

	    request from the client, reply to it, then receive another

	    not know in advance how long they will be serving the

	    not know in advance how long they will be serving the

	    client.  Such servers usually start a new process for each

	    client.  Such servers usually start a new process for each

	    client.  While the new process is serving its client, the

	    client.  While the new process is serving its client, the

	    (&man.make.1;, &man.system.3;, &man.popen.3;, and

	    (&man.make.1;, &man.system.3;, &man.popen.3;, and

	    analogues in higher-level scripting languages like Perl

	    analogues in higher-level scripting languages like Perl

	    and Tcl) are specified to use the Bourne shell to

	    and Tcl) are specified to use the Bourne shell to

	    and widely used, it is important for it to be quick to

	    and widely used, it is important for it to be quick to

	    start, be deterministic in its behavior, and have a small

	    start, be deterministic in its behavior, and have a small

	    memory footprint.</para>

	    memory footprint.</para>

	</question>

	</question>

	<answer>

	<answer>

	    unexpectedly.  To disable them, set

	    unexpectedly.  To disable them, set

	    <varname>net.link.ether.inet.log_arp_wrong_iface</varname>

	    <varname>net.link.ether.inet.log_arp_wrong_iface</varname>

	    to <literal>0</literal>.</para>

	    to <literal>0</literal>.</para>

	</callout>

	</callout>

	<callout arearefs="co-manpages-macro-example-ls-8">

	<callout arearefs="co-manpages-macro-example-ls-8">

	    is specified for the argument, the default of

	    is specified for the argument, the default of

	    <literal>file ...</literal> is used.</para>

	    <literal>file ...</literal> is used.</para>

	</callout>

	</callout>

A         Makefile</screen>

A         Makefile</screen>

	  <para>Check the contents of the

	  <para>Check the contents of the

	    article, in this case the <filename>Makefile</filename>

	    article, in this case the <filename>Makefile</filename>

	    can be used unchanged.  The <literal>$&os;...$</literal>

	    can be used unchanged.  The <literal>$&os;...$</literal>

	    version string on the second line will be replaced by the

	    version string on the second line will be replaced by the

      <procedure>

      <procedure>

	<step>

	<step>

	    is a book, the generated document is

	    is a book, the generated document is

	    <filename>book.xml</filename>.</para>

	    <filename>book.xml</filename>.</para>

	<step>

	<step>

	  <para>Set the <acronym>MIME</acronym> types of the files.

	  <para>Set the <acronym>MIME</acronym> types of the files.

	    version control system from mistaking these files for

	    version control system from mistaking these files for

	    binary data, the <literal>fbsd:notbinary</literal>

	    binary data, the <literal>fbsd:notbinary</literal>

	    property is also set:</para>

	    property is also set:</para>

    <para>A tag is used to identify where a particular element starts,

    <para>A tag is used to identify where a particular element starts,

      and where the element ends.  <emphasis>The tag is not part of

      and where the element ends.  <emphasis>The tag is not part of

      normally written to mark up specific types of information, each

      normally written to mark up specific types of information, each

      one will recognize different elements, and will therefore have

      one will recognize different elements, and will therefore have

      different names for the tags.</para>

      different names for the tags.</para>

	      council delegated this to the American National

	      council delegated this to the American National

	      Standards Institute (<acronym>ANSI</acronym>).</para>

	      Standards Institute (<acronym>ANSI</acronym>).</para>

	      the owner string is <literal>-//&os;</literal>.  As seen

	      the owner string is <literal>-//&os;</literal>.  As seen

	      in the example, the <acronym>W3C</acronym> are not a

	      in the example, the <acronym>W3C</acronym> are not a

	      registered owner either.</para>

	      registered owner either.</para>

	</step>

	</step>

	<step>

	<step>

	    &man.inetd.8; is owned by

	    &man.inetd.8; is owned by

	    <systemitem class="username">root</systemitem>, use

	    <systemitem class="username">root</systemitem>, use

	    &man.su.1; to become

	    &man.su.1; to become

      <primary>editors</primary>

      <primary>editors</primary>

    </indexterm>

    </indexterm>

      text editor.  &os; comes with a few as part of the base system,

      text editor.  &os; comes with a few as part of the base system,

      and many more are available in the Ports Collection.</para>

      and many more are available in the Ports Collection.</para>

      <title>Stage One and Stage Two</title>

      <title>Stage One and Stage Two</title>

      <para>Conceptually, the first and second stages are part of the

      <para>Conceptually, the first and second stages are part of the

	constraints, they have been split into two, but are always

	constraints, they have been split into two, but are always

	installed together.  They are copied from the combined

	installed together.  They are copied from the combined

	<filename>/boot/boot</filename> by the &os; installer or

	<filename>/boot/boot</filename> by the &os; installer or

	  Network Driver Interface Specification

	  Network Driver Interface Specification

	  (<acronym>NDIS</acronym>).  It includes &man.ndisgen.8;

	  (<acronym>NDIS</acronym>).  It includes &man.ndisgen.8;

	  which can be used to convert a &windowsxp; driver into a

	  which can be used to convert a &windowsxp; driver into a

	  driver uses a &windowsxp; binary, it only runs on &i386;

	  driver uses a &windowsxp; binary, it only runs on &i386;

	  and amd64 systems.  <acronym>PCI</acronym>, CardBus,

	  and amd64 systems.  <acronym>PCI</acronym>, CardBus,

	  <acronym>PCMCIA</acronym>, and <acronym>USB</acronym>

	  <acronym>PCMCIA</acronym>, and <acronym>USB</acronym>

	  referred to as <emphasis>journaling</emphasis>.

	  referred to as <emphasis>journaling</emphasis>.

	  Meta-data updates are still written synchronously, but only

	  Meta-data updates are still written synchronously, but only

	  into a small region of the disk.  Later on, they are moved

	  into a small region of the disk.  Later on, they are moved

	  small, contiguous region on the disk, there are no long

	  small, contiguous region on the disk, there are no long

	  distances for the disk heads to move, even during heavy

	  distances for the disk heads to move, even during heavy

	  operations, so these operations are quicker than synchronous

	  operations, so these operations are quicker than synchronous

      <screen>&prompt.root; <userinput>gmirror clear ada8</userinput></screen>

      <screen>&prompt.root; <userinput>gmirror clear ada8</userinput></screen>

      <para>&man.gmirror.8; stores one block of metadata at the end of

      <para>&man.gmirror.8; stores one block of metadata at the end of

	also store metadata at the end of the disk, mirroring entire

	also store metadata at the end of the disk, mirroring entire

	<acronym>GPT</acronym> disks with &man.gmirror.8; is not

	<acronym>GPT</acronym> disks with &man.gmirror.8; is not

	recommended.  <acronym>MBR</acronym> partitioning is used here

	recommended.  <acronym>MBR</acronym> partitioning is used here

      <para>Reboot the system to test the new mirror and verify that

      <para>Reboot the system to test the new mirror and verify that

	all data has been copied.  The <acronym>BIOS</acronym> will

	all data has been copied.  The <acronym>BIOS</acronym> will

	see the mirror as two individual drives rather than a mirror.

	see the mirror as two individual drives rather than a mirror.

	selected to boot.</para>

	selected to boot.</para>

      <para>See <xref linkend="gmirror-troubleshooting"/> if there are

      <para>See <xref linkend="gmirror-troubleshooting"/> if there are

    <para>A better solution is to use <command>glabel</command> to

    <para>A better solution is to use <command>glabel</command> to

      label the disk devices and use the labels in

      label the disk devices and use the labels in

      <command>glabel</command> stores the label in the last sector of

      <command>glabel</command> stores the label in the last sector of

      reboots.  By using this label as a device, the file system may

      reboots.  By using this label as a device, the file system may

      always be mounted regardless of what device node it is accessed

      always be mounted regardless of what device node it is accessed

      through.</para>

      through.</para>

	    an <application>&xorg;</application> extension which

	    an <application>&xorg;</application> extension which

	    allows a program to bypass the

	    allows a program to bypass the

	    <application>&xorg;</application> server and directly

	    <application>&xorg;</application> server and directly

	    memory mapping, programs using it must be run as

	    memory mapping, programs using it must be run as

	    <systemitem class="username">root</systemitem>.  The

	    <systemitem class="username">root</systemitem>.  The

	    <acronym>DGA</acronym> extension can be tested and

	    <acronym>DGA</acronym> extension can be tested and

      The authentication system keeps track of the last one-time

      The authentication system keeps track of the last one-time

      password used, and the user is authenticated if the hash of the

      password used, and the user is authenticated if the hash of the

      user-provided password is equal to the previous password.

      user-provided password is equal to the previous password.

      future one-time passwords if a successfully used password is

      future one-time passwords if a successfully used password is

      captured.  The iteration count is decremented after each

      captured.  The iteration count is decremented after each

      successful login to keep the user and the login program in sync.

      successful login to keep the user and the login program in sync.

	<quote>trusted third party</quote> of the system.  It is the

	<quote>trusted third party</quote> of the system.  It is the

	computer that issues <application>Kerberos</application>

	computer that issues <application>Kerberos</application>

	tickets, which are used for clients to authenticate to

	tickets, which are used for clients to authenticate to

	trusted by all other computers in the

	trusted by all other computers in the

	<application>Kerberos</application> realm, it has heightened

	<application>Kerberos</application> realm, it has heightened

	security concerns.  Direct access to the KDC should be

	security concerns.  Direct access to the KDC should be

      device provides a 16-character buffer, which allows for better

      device provides a 16-character buffer, which allows for better

      system performance.  Bugs in plain 16550 devices prevent the use

      system performance.  Bugs in plain 16550 devices prevent the use

      of the 16-character buffer, so use 16550A devices if possible.

      of the 16-character buffer, so use 16550A devices if possible.

      operating system than the 16-character-buffer devices,

      operating system than the 16-character-buffer devices,

      16550A-based serial interface cards are preferred.  If the

      16550A-based serial interface cards are preferred.  If the

      system has many active serial ports or will have a heavy load,

      system has many active serial ports or will have a heavy load,

      <para>The second method is to configure the

      <para>The second method is to configure the

	<acronym>RS-232</acronym> interface to vary its speed based on

	<acronym>RS-232</acronym> interface to vary its speed based on

	<command>getty</command> does not understand any particular

	<command>getty</command> does not understand any particular

	modem's connection speed reporting, it gives a

	modem's connection speed reporting, it gives a

	<prompt>login:</prompt> message at an initial speed and

	<prompt>login:</prompt> message at an initial speed and

	2 TB drive.  The usable space is 1 TB.  When the

	2 TB drive.  The usable space is 1 TB.  When the

	1 TB drive is replaced with another 2 TB drive, the

	1 TB drive is replaced with another 2 TB drive, the

	resilvering process copies the existing data onto the new

	resilvering process copies the existing data onto the new

	both of the devices now have 2 TB capacity, the mirror's

	both of the devices now have 2 TB capacity, the mirror's

	available space can be grown to 2&nbsp;TB.</para>

	available space can be grown to 2&nbsp;TB.</para>

	      Clones can be <emphasis>promoted</emphasis>, reversing

	      Clones can be <emphasis>promoted</emphasis>, reversing

	      this dependency and making the clone the parent and the

	      this dependency and making the clone the parent and the

	      previous parent the child.  This operation requires no

	      previous parent the child.  This operation requires no

	      the parent and child is reversed, existing quotas and

	      the parent and child is reversed, existing quotas and

	      reservations might be affected.</entry>

	      reservations might be affected.</entry>

	  </row>

	  </row>

	      blocks will be checked byte-for-byte to ensure it is

	      blocks will be checked byte-for-byte to ensure it is

	      actually identical.  If the data is not identical, the

	      actually identical.  If the data is not identical, the

	      hash collision will be noted and the two blocks will be

	      hash collision will be noted and the two blocks will be

	      store the hash of each unique block, it consumes a very

	      store the hash of each unique block, it consumes a very

	      large amount of memory.  A general rule of thumb is

	      large amount of memory.  A general rule of thumb is

	      5-6 GB of ram per 1 TB of deduplicated data).

	      5-6 GB of ram per 1 TB of deduplicated data).