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Editorial review of Implementation Differences in DTrace.

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Need to collaborate with someone who knows more about
DTrace to finish the review of the rest of this chapter.

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Dru Lavigne 2014-04-07 15:12:06 +00:00
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en_US.ISO8859-1/books/handbook/dtrace/chapter.xml
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@ -103,52 +103,50 @@ that might make this chapter too large.
<sect1 xml:id="dtrace-implementation">
<title>Implementation Differences</title>
<para>While the &dtrace; in &os; is very similar to that found
in &solaris;, differences exist that should be explained before
continuing. The primary difference users will notice is that
on &os;, &dtrace; needs to be specifically enabled. There are
kernel options and modules which must be enabled for &dtrace; to
work properly. These will be explained later.</para>
<para>While the &dtrace; in &os; is similar to that found
in &solaris;, differences do exist.
The primary difference is that
on &os;, &dtrace; needs to be specifically enabled by loading
kernel modules or by compiling a custom kernel with specific
options.</para>
<para>There is a <literal>DDB_CTF</literal> kernel option which
is used to enable support for loading the <acronym>CTF</acronym>
<para>&os; uses the <literal>DDB_CTF</literal> kernel option
to enable support for loading <acronym>CTF</acronym>
data from kernel modules and the kernel itself.
<acronym>CTF</acronym> is the &solaris; Compact C Type Format
which encapsulates a reduced form of debugging information
similar to <acronym>DWARF</acronym> and the venerable stabs.
This <acronym>CTF</acronym> data is added to the binaries by the
<acronym>CTF</acronym> data is added to binaries by the
<command>ctfconvert</command> and <command>ctfmerge</command>
build tools. The <command>ctfconvert</command> utility parses
<acronym>DWARF</acronym> <acronym>ELF</acronym> debug sections
created by the compiler and <command>ctfmerge</command> merges
<acronym>CTF</acronym> <acronym>ELF</acronym> sections from
objects into either executables or shared libraries. More on
how to enable this for the kernel and &os; build is
forthcoming.</para>
objects into either executables or shared libraries.</para>
<para>Some different providers exist for &os; than for &solaris;.
Most notable is the <literal>dtmalloc</literal> provider, which
allows tracing <function>malloc()</function> by type in the
&os; kernel.</para>
<para>Only <systemitem class="username">root</systemitem> may use &dtrace; on &os;.
This is related to security differences, &solaris; has a few
<para>Due to security differences, only <systemitem
class="username">root</systemitem> may use &dtrace; on &os;.
&solaris; has a few
low level security checks which do not yet exist in &os;. As
such, the <filename>/dev/dtrace/dtrace</filename> is
strictly limited to <systemitem class="username">root</systemitem> users only.</para>
strictly limited to <systemitem class="username">root</systemitem>.</para>
<para>Finally, the &dtrace; software falls under &sun;'s
<acronym>CDDL</acronym> license. The <literal>Common
Development and Distribution License</literal> comes with &os;,
see the
<para>&dtrace; falls under &sun;'s Common
Development and Distribution License
(<acronym>CDDL</acronym>) license. To view this license on &os;,
see
<filename>/usr/src/cddl/contrib/opensolaris/OPENSOLARIS.LICENSE</filename>
or view it online at
<uri xlink:href="http://www.opensolaris.org/os/licensing">http://www.opensolaris.org/os/licensing</uri>.</para>
<para>This license means that a &os; kernel with the &dtrace;
options is still <acronym>BSD</acronym> licensed; however
the <acronym>CDDL</acronym> kicks in when the modules are
distributed in binary form, or the binaries are loaded.</para>
<uri xlink:href="http://www.opensolaris.org/os/licensing">http://www.opensolaris.org/os/licensing</uri>.
While a &os; kernel with &dtrace; support
is <acronym>BSD</acronym> licensed,
the <acronym>CDDL</acronym> is used when the modules are
distributed in binary form or the binaries are loaded.</para>
</sect1>
<sect1 xml:id="dtrace-enable">