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 112 <li class="toctree-l2 current"><a class="current reference internal" href="#">Firewall FAQ</a><ul>
 113 <li class="toctree-l3"><a class="reference internal" href="#can-i-directly-write-to-firewall-configuration-registers">Can I directly write to firewall configuration registers ?</a></li>
 114 <li class="toctree-l3"><a class="reference internal" href="#how-do-i-configure-a-firewall">How do I configure a firewall ?</a></li>
 115 <li class="toctree-l3"><a class="reference internal" href="#how-do-i-specify-which-firewall-to-program">How do I specify which firewall to program ?</a></li>
 116 <li class="toctree-l3"><a class="reference internal" href="#how-do-i-know-what-permissions-to-program-in-the-firewall">How do I know what permissions to program in the firewall ?</a></li>
 117 <li class="toctree-l3"><a class="reference internal" href="#are-all-firewalls-user-programmable">Are all firewalls user programmable ?</a></li>
 118 <li class="toctree-l3"><a class="reference internal" href="#what-is-firewall-ownership">What is firewall ownership ?</a></li>
 119 <li class="toctree-l3"><a class="reference internal" href="#is-there-any-relationship-between-ownership-and-firewall-permissions">Is there any relationship between ownership and firewall permissions ?</a></li>
 120 <li class="toctree-l3"><a class="reference internal" href="#is-host-id-the-same-as-priv-id">Is host ID the same as priv ID ?</a></li>
 121 <li class="toctree-l3"><a class="reference internal" href="#is-programming-overlapping-firewalls-supported">Is programming overlapping firewalls supported ?</a></li>
 122 <li class="toctree-l3"><a class="reference internal" href="#what-are-background-and-foreground-regions">What are background and foreground regions ?</a></li>
 123 <li class="toctree-l3"><a class="reference internal" href="#how-do-i-debug-firewall-issues">How do I debug firewall issues ?</a></li>
 124 <li class="toctree-l3"><a class="reference internal" href="#how-are-dmsc-managed-resources-firewalled">How are DMSC-managed resources firewalled ?</a></li>
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 176   <div class="section" id="firewall-faq">
 177 <h1>Firewall FAQ<a class="headerlink" href="#firewall-faq" title="Permalink to this headline">¶</a></h1>
 178 <div class="contents local topic" id="contents">
 179 <ul class="simple">
 180 <li><a class="reference internal" href="#can-i-directly-write-to-firewall-configuration-registers" id="id1">Can I directly write to firewall configuration registers ?</a></li>
 181 <li><a class="reference internal" href="#how-do-i-configure-a-firewall" id="id2">How do I configure a firewall ?</a></li>
 182 <li><a class="reference internal" href="#how-do-i-specify-which-firewall-to-program" id="id3">How do I specify which firewall to program ?</a></li>
 183 <li><a class="reference internal" href="#how-do-i-know-what-permissions-to-program-in-the-firewall" id="id4">How do I know what permissions to program in the firewall ?</a></li>
 184 <li><a class="reference internal" href="#are-all-firewalls-user-programmable" id="id5">Are all firewalls user programmable ?</a></li>
 185 <li><a class="reference internal" href="#what-is-firewall-ownership" id="id6">What is firewall ownership ?</a></li>
 186 <li><a class="reference internal" href="#is-there-any-relationship-between-ownership-and-firewall-permissions" id="id7">Is there any relationship between ownership and firewall permissions ?</a></li>
 187 <li><a class="reference internal" href="#is-host-id-the-same-as-priv-id" id="id8">Is host ID the same as priv ID ?</a></li>
 188 <li><a class="reference internal" href="#is-programming-overlapping-firewalls-supported" id="id9">Is programming overlapping firewalls supported ?</a></li>
 189 <li><a class="reference internal" href="#what-are-background-and-foreground-regions" id="id10">What are background and foreground regions ?</a></li>
 190 <li><a class="reference internal" href="#how-do-i-debug-firewall-issues" id="id11">How do I debug firewall issues ?</a></li>
 191 <li><a class="reference internal" href="#how-are-dmsc-managed-resources-firewalled" id="id12">How are DMSC-managed resources firewalled ?</a></li>
 192 </ul>
 193 </div>
 194 <div class="admonition note">
 195 <p class="first admonition-title">Note</p>
 196 <p class="last">System Firmware supports multiple SOC’s.
 197 When providing links to SOC-specific documentation, this document provides
 198 the example of AM65x SR1 SOC.
 199 Documentation for other SOC’s can be found by traversing similar path from
 200 the root of <a class="reference internal" href="../5_soc_doc/index.html"><span class="doc">Chapter 5: SoC Family Specific Documentation</span></a>.</p>
 201 </div>
 202 <div class="section" id="can-i-directly-write-to-firewall-configuration-registers">
 203 <h2><a class="toc-backref" href="#id1">Can I directly write to firewall configuration registers ?</a><a class="headerlink" href="#can-i-directly-write-to-firewall-configuration-registers" title="Permalink to this headline">¶</a></h2>
 204 <p>No. Firewall configuration registers are only writable by System Firmware.
 205 They cannot be programmed by direct register writes.</p>
 206 </div>
 207 <div class="section" id="how-do-i-configure-a-firewall">
 208 <h2><a class="toc-backref" href="#id2">How do I configure a firewall ?</a><a class="headerlink" href="#how-do-i-configure-a-firewall" title="Permalink to this headline">¶</a></h2>
 209 <p>Firewalls are configured using the <a class="reference internal" href="../2_tisci_msgs/security/firewall_api.html#set-firewall-region"><span class="std std-ref">TISCI_MSG_SET_FWL_REGION</span></a> TISCI message.</p>
 210 <p>Disabling a firewall is also done using the same API using the control word.</p>
 211 <p>All the registers of a firewall can be configured using the above TISCI message.</p>
 212 </div>
 213 <div class="section" id="how-do-i-specify-which-firewall-to-program">
 214 <h2><a class="toc-backref" href="#id3">How do I specify which firewall to program ?</a><a class="headerlink" href="#how-do-i-specify-which-firewall-to-program" title="Permalink to this headline">¶</a></h2>
 215 <p>Firewalls are identified to System Firmware by their ID.
 216 The ID of a firewall can be obtained from the Technical Reference Manual(TRM) of the SOC.
 217 Information on firewalls is provided in the chapter “System Interconnect” and the subsection
 218 “Interconnect Firewalls”.</p>
 219 <p><a class="reference internal" href="../2_tisci_msgs/security/firewall_api.html#set-firewall-region"><span class="std std-ref">TISCI_MSG_SET_FWL_REGION</span></a> TISCI message takes firewall id as one of the arguments.</p>
 220 </div>
 221 <div class="section" id="how-do-i-know-what-permissions-to-program-in-the-firewall">
 222 <h2><a class="toc-backref" href="#id4">How do I know what permissions to program in the firewall ?</a><a class="headerlink" href="#how-do-i-know-what-permissions-to-program-in-the-firewall" title="Permalink to this headline">¶</a></h2>
 223 <p>Privilege ID’s of the various initiators are described in the public SOC documentation
 224 <a class="reference internal" href="../5_soc_doc/index.html"><span class="doc">Chapter 5: SoC Family Specific Documentation</span></a> under “&lt;SOC&gt; Firewall Descriptions”.
 225 As an example for AM65X devices, this is listed under
 226 <a class="reference internal" href="../5_soc_doc/am6x/firewalls.html#soc-doc-am6-public-fwl-desc-priv-id-list"><span class="std std-ref">AM65x List of priv ids</span></a>.</p>
 227 <p>The values to program in the permission bits and the control registers
 228 can be found from the below section in the TRM.</p>
 229 <p>“System Interconnect” -&gt; “System Interconnect Registers” -&gt; “Firewall Region Registers”</p>
 230 </div>
 231 <div class="section" id="are-all-firewalls-user-programmable">
 232 <h2><a class="toc-backref" href="#id5">Are all firewalls user programmable ?</a><a class="headerlink" href="#are-all-firewalls-user-programmable" title="Permalink to this headline">¶</a></h2>
 233 <p>No. System Firmware maintains ownership of the following categories of firewalls.</p>
 234 <ol class="arabic simple">
 235 <li>Firewalls protecting DMSC-owned resources - e.g. secure proxies,
 236 firewall configuration port etc.
 237 These firewalls are marked as owned by <code class="docutils literal"><span class="pre">dmsc</span></code> in the firewall SOC data.</li>
 238 <li>Firewalls protecting DMSC-managed resources i.e. NAVSS resources managed by RM.
 239 These firewalls are marked as owned by <code class="docutils literal"><span class="pre">rm</span></code> in the firewall SOC data.</li>
 240 </ol>
 241 <p>The remaining firewalls are user programmable through the TISCI interface only.</p>
 242 <p>The list of firewalls owned/initialized by System Firmware are listed for AM65X SR1
 243 devices at</p>
 244 <ul class="simple">
 245 <li><a class="reference internal" href="../5_soc_doc/am6x/firewalls.html#soc-doc-am6-public-fwl-desc-region-fwl-list"><span class="std std-ref">AM65x Standard region-based slave firewall configuration</span></a></li>
 246 <li><a class="reference internal" href="../5_soc_doc/am6x/firewalls.html#soc-doc-am6-public-fwl-desc-channel-fwl-list"><span class="std std-ref">AM65x Channelized slave firewall configuration</span></a></li>
 247 </ul>
 248 </div>
 249 <div class="section" id="what-is-firewall-ownership">
 250 <h2><a class="toc-backref" href="#id6">What is firewall ownership ?</a><a class="headerlink" href="#what-is-firewall-ownership" title="Permalink to this headline">¶</a></h2>
 251 <p>Firewall ownership is a software concept implemented by System Firmware.
 252 A firewall region can be marked as owned by a specific host.
 253 This prevents the firewall region from being programmed/reprogrammed
 254 by another host and helps in firewall overlap checks.</p>
 255 <p>By default, only firewalls required from System Firmware use are marked as owned by <code class="docutils literal"><span class="pre">dmsc</span></code> or <code class="docutils literal"><span class="pre">rm</span></code>.
 256 Rest of the firewalls have ownership set to <code class="docutils literal"><span class="pre">none</span></code>.
 257 Firewalls with owner set as <code class="docutils literal"><span class="pre">none</span></code> can be programmed by any host.</p>
 258 <p>A host can claim ownership of a firewall region with owner set to <code class="docutils literal"><span class="pre">none</span></code> by using the
 259 <a class="reference internal" href="../2_tisci_msgs/security/firewall_api.html#change-firewall-owner"><span class="std std-ref">TISCI_MSG_CHANGE_FWL_OWNER</span></a> message. A host
 260 can use the same message to transfer a firewall region it owns to another host.</p>
 261 </div>
 262 <div class="section" id="is-there-any-relationship-between-ownership-and-firewall-permissions">
 263 <h2><a class="toc-backref" href="#id7">Is there any relationship between ownership and firewall permissions ?</a><a class="headerlink" href="#is-there-any-relationship-between-ownership-and-firewall-permissions" title="Permalink to this headline">¶</a></h2>
 264 <p>The concept of firewall ownership is unrelated to firewall permissions.
 265 Firewall ownership is a software concept.
 266 Firewall permissions directly map to the underlying hardware registers.
 267 The owner of a firewall can configure firewall permissions as desired.
 268 System Firmware does not perform any checks on the firewall permissions supplied
 269 in the TISCI message arguments.</p>
 270 </div>
 271 <div class="section" id="is-host-id-the-same-as-priv-id">
 272 <h2><a class="toc-backref" href="#id8">Is host ID the same as priv ID ?</a><a class="headerlink" href="#is-host-id-the-same-as-priv-id" title="Permalink to this headline">¶</a></h2>
 273 <p>No. Host ID is a software concept introduced by System Firmware to be differentiate
 274 between different entities on the device.
 275 Some of the entities can be on the same core.
 276 e.g. privileged software and unprivileged software running on the same core.
 277 See <a class="reference internal" href="../5_soc_doc/am6x/hosts.html#soc-doc-am6-public-host-desc-intro"><span class="std std-ref">AM65X Host IDs</span></a>.</p>
 278 <p>Priv ID is a hardware concept. Every transaction on the interconnect has various
 279 attributes including but not limited to Priv ID, user/privileged, secure/non
 280 secure. Each host maps to a Priv ID. See <a class="reference internal" href="../5_soc_doc/am6x/firewalls.html#soc-doc-am6-public-fwl-desc-priv-id-list"><span class="std std-ref">AM65x List of priv ids</span></a> for the mapping.</p>
 281 </div>
 282 <div class="section" id="is-programming-overlapping-firewalls-supported">
 283 <h2><a class="toc-backref" href="#id9">Is programming overlapping firewalls supported ?</a><a class="headerlink" href="#is-programming-overlapping-firewalls-supported" title="Permalink to this headline">¶</a></h2>
 284 <p>Yes. Programming overlapping firewalls is supported.
 285 System Firmware performs additional checks when overlapping firewall regions are being programmed.</p>
 286 <ol class="arabic simple">
 287 <li>A background region cannot overlap with another background region.</li>
 288 <li>A foreground region cannot overlap with another foreground region.</li>
 289 </ol>
 290 <p>The above two checks are to prevent undefined behaviour as per hardware specification.</p>
 291 <ol class="arabic simple" start="3">
 292 <li>Same host must own both the foreground and background region in case of an overlap.
 293 This check prevents one host from using a foreground region to override
 294 firewall configuration performed by another host</li>
 295 </ol>
 296 <p>Before programming overlapping firewall regions, please claim ownership of both the
 297 regions using the <a class="reference internal" href="../2_tisci_msgs/security/firewall_api.html#change-firewall-owner"><span class="std std-ref">TISCI_MSG_CHANGE_FWL_OWNER</span></a> message.</p>
 298 </div>
 299 <div class="section" id="what-are-background-and-foreground-regions">
 300 <h2><a class="toc-backref" href="#id10">What are background and foreground regions ?</a><a class="headerlink" href="#what-are-background-and-foreground-regions" title="Permalink to this headline">¶</a></h2>
 301 <p>The firewall IP supports the concept for foreground and background regions.
 302 The firewall permissions specified in a background region can be overridden
 303 by using a foreground region.</p>
 304 <p>A region can be specified as foreground or background using a bit in the control register.
 305 Please refer to the following section in TRM for more information.</p>
 306 <p>“System Interconnect” -&gt; “System Interconnect Registers” -&gt; “Firewall Region Registers”</p>
 307 <p>Following restrictions apply from hardware perspective.</p>
 308 <ol class="arabic simple">
 309 <li>A background region cannot overlap with another background region.</li>
 310 <li>A foreground region cannot overlap with another foreground region.</li>
 311 <li>A foreground region cannot span two background regions.</li>
 312 </ol>
 313 </div>
 314 <div class="section" id="how-do-i-debug-firewall-issues">
 315 <h2><a class="toc-backref" href="#id11">How do I debug firewall issues ?</a><a class="headerlink" href="#how-do-i-debug-firewall-issues" title="Permalink to this headline">¶</a></h2>
 316 <p>The programmed firewall settings can be read back by the owner using
 317 <a class="reference internal" href="../2_tisci_msgs/security/firewall_api.html#get-firewall-region"><span class="std std-ref">TISCI_MSG_GET_FWL_REGION</span></a>.</p>
 318 <p>Direct readback of the firewall configuration registers is not currently
 319 allowed.</p>
 320 <p>When a firewall exception occurs, the exception data is sent out via the
 321 enabled trace method.
 322 The data sent out is the dump of the firewall exception registers as
 323 defined in below section in the corresponding device TRM.</p>
 324 <p>“System Interconnect” -&gt; “System Interconnect Registers” -&gt; “Firewall Exception Registers”</p>
 325 <div class="code highlight-cpp"><div class="highlight"><pre><span></span><span class="n">FWL</span> <span class="n">Exception</span>  <span class="mh">0x1116100</span>
 326 <span class="mh">0x70000</span>
 327 <span class="mh">0x70000000</span>
 328 <span class="mh">0x0</span>
 329 <span class="mh">0xE022000</span>
 330 <span class="mh">0x8</span>
 331 </pre></div>
 332 </div>
 333 <p>The 6 hex values shown above correspond to the 2 exception header registers and
 334 4 exception data registers in the order shown in the TRM.</p>
 335 <div class="admonition warning">
 336 <p class="first admonition-title">Warning</p>
 337 <p class="last">Please note that this format is being deprecated in favour of a binary format
 338 in conformance with the rest of traces supplied by System Firmware.</p>
 339 </div>
 340 </div>
 341 <div class="section" id="how-are-dmsc-managed-resources-firewalled">
 342 <h2><a class="toc-backref" href="#id12">How are DMSC-managed resources firewalled ?</a><a class="headerlink" href="#how-are-dmsc-managed-resources-firewalled" title="Permalink to this headline">¶</a></h2>
 343 <p>NAVSS resources managed by DMSC (UDMA channels, Rings, Proxy channels and IRQ)
 344 are firewalled automatically when the corresponding RM TISCI messages are sent.</p>
 345 <p>Accessing these resources before sending the corresponding RM TISCI message
 346 will result in a firewall exception.</p>
 347 </div>
 348 </div>
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