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   <section id="skiboot-6-0-18">
 <span id="id1"></span><h1>skiboot-6.0.18<a class="headerlink" href="#skiboot-6-0-18" title="Link to this heading">¶</a></h1>
 <p>skiboot 6.0.18 was released on Wednesday March 6th, 2019. It replaces
 <a class="reference internal" href="skiboot-6.0.17.html#skiboot-6-0-17"><span class="std std-ref">skiboot-6.0.17</span></a> as the current stable release in the 6.0.x series.</p>
 <p>It is recommended that 6.0.18 be used instead of any previous 6.0.x version
 due to the bug fixes it contains.</p>
 <p>Over <a class="reference internal" href="skiboot-6.0.17.html#skiboot-6-0-17"><span class="std std-ref">skiboot-6.0.17</span></a> we have several bug fixes, including important ones
 for powercap, ipmi-hiomap and BMC communication driver.</p>
 <section id="powercap">
 <h2>powercap<a class="headerlink" href="#powercap" title="Link to this heading">¶</a></h2>
 <ul>
 <li><p>powercap: occ: Fix the powercapping range allowed for user</p>
 <p>OCC provides two limits for minimum powercap. One being hard powercap
 minimum which is guaranteed by OCC and the other one is a soft
 powercap minimum which is lesser than hard-min and may or may not be
 asserted due to various power-thermal reasons. So to allow the users
 to access the entire powercap range, this patch exports soft powercap
 minimum as the “powercap-min” DT property. And it also adds a new
 DT property called “powercap-hard-min” to export the hard-min powercap
 limit.</p>
 </li>
 </ul>
 </section>
 <section id="ipmi-hiomap">
 <h2>IPMI-HIOMAP<a class="headerlink" href="#ipmi-hiomap" title="Link to this heading">¶</a></h2>
 <ul>
 <li><p>ipmi-hiomap test case enhancements/fixes.</p></li>
 <li><p>libflash/ipmi-hiomap: Enforce message size for empty response</p>
 <p>The protocol defines the response to the associated messages as empty
 except for the command ID and sequence fields. If the BMC is returning
 extra data consider the message malformed.</p>
 </li>
 <li><p>libflash/ipmi-hiomap: Remove unused close handling</p>
 <p>Issuing a HIOMAP_C_CLOSE is not required by the protocol specification,
 rather a close can be implicit in a subsequent
 CREATE_{READ,WRITE}_WINDOW request. The implicit close provides an
 opportunity to reduce LPC traffic and the implementation takes up that
 optimisation, so remove the case from the IPMI callback handler.</p>
 </li>
 <li><p>libflash/ipmi-hiomap: Overhaul event handling</p>
 <p>Reworking the event handling was inspired by a bug report by Vasant
 where the host would get wedged on multiple flash access attempts in the
 face of a persistent error state on the BMC-side. The cause of this bug
 was the early-exit based on ctx-&gt;update, which erronously assumed that
 all events had been completely handled in prior calls to
 ipmi_hiomap_handle_events(). This is not true if e.g.
 HIOMAP_E_DAEMON_READY is clear in the prior calls.</p>
 <p>Regardless, there were other correctness and efficiency problems with
 the handling strategy:</p>
 <ul class="simple">
 <li><p>Ack-able event state was not restored in the face of errors in the
 process of re-establishing protocol state</p></li>
 <li><p>It forced needless window restoration with respect to the context in
 which ipmi_hiomap_handle_events() was called.</p></li>
 <li><p>Tests for HIOMAP_E_DAEMON_READY and HIOMAP_E_FLASH_LOST were redundant
 with the overhauled error handling introduced in the previous patch</p></li>
 </ul>
 <p>Fix all of the above issues and add comments to explain the event
 handling flow.</p>
 <p>Tests for correctness follow later in the series.</p>
 </li>
 <li><p>libflash/ipmi-hiomap: Overhaul error handling</p>
 <p>The aim is to improve the robustness with respect to absence of the
 BMC-side daemon. The current error handling roughly mirrors what was
 done for the mailbox implementation, but there’s room for improvement.</p>
 <p>Errors are split into two classes, those that affect the transport state
 and those that affect the window validity. From here, we push the
 transport state error checks right to the bottom of the stack, to ensure
 the link is known to be in a good state before any message is sent.
 Window validity tests remain as they were in the hiomap_window_move()
 and ipmi_hiomap_read() functions. Validity tests are not necessary in
 the write and erase paths as we will receive an error response from the
 BMC when performing a dirty or flush on an invalid window.</p>
 <p>Recovery also remains as it was, done on entry to the blocklevel
 callbacks. If an error state is encountered in the middle of an
 operation no attempt is made to recover it on the spot, instead the
 error is returned up the stack and the caller can choose how it wishes
 to respond.</p>
 </li>
 <li><p>libflash/ipmi-hiomap: Fix leak of msg in callback</p></li>
 </ul>
 </section>
 <section id="bmc-communication">
 <h2>BMC communication<a class="headerlink" href="#bmc-communication" title="Link to this heading">¶</a></h2>
 <ul>
 <li><p>core/ipmi: Add ipmi sync messages to top of the list</p>
 <p>In ipmi_queue_msg_sync() path OPAL will wait until it gets response from
 BMC. If we do not get response ontime we may endup in kernel hardlockups.
 Hence lets add sync messages to top of the queue. This will reduces the
 chance of hardlockups.</p>
 </li>
 <li><p>hw/bt: Introduce separate list for synchronous messages</p>
 <p>BT send logic always sends top of bt message list to BMC. Once BMC reads the
 message, it clears the interrupt and bt_idle() becomes true.</p>
 <p>bt_add_ipmi_msg_head() adds message to top of the list. If bt message list
 is not empty then:</p>
 <blockquote>
 <div><ul class="simple">
 <li><p>if bt_idle() is true then we will endup sending message to BMC before
 getting response from BMC for inflight message. Looks like on some
 BMC implementation this results in message timeout.</p></li>
 <li><p>else we endup starting message timer without actually sending message
 to BMC.. which is not correct.</p></li>
 </ul>
 </div></blockquote>
 <p>This patch introduces separate list to track synchronous messages.
 bt_add_ipmi_msg_head() will add messages to tail of this new list. We
 will always process this queue before processing normal queue.</p>
 <p>Finally this patch introduces new variable (inflight_bt_msg) to track
 inflight message. This will point to current inflight message.</p>
 </li>
 <li><p>hw/bt: Fix message retry handler</p>
 <p>In some corner cases (like BMC reboot), bt_send_and_unlock() starts
 message timer, but won’t send message to BMC as driver is not free to
 send message. bt_expire_old_msg() function enables H2B interrupt without
 actually sending message.</p>
 <p>This patch fixes above issue.</p>
 </li>
 <li><p>ipmi/power: Fix system reboot issue</p>
 <p>Kernel makes reboot/shudown OPAL call for reboot/shutdown. Once kernel
 gets response from OPAL it runs opal_poll_events() until firmware
 handles the request.</p>
 <p>On BMC based system, OPAL makes IPMI call (IPMI_CHASSIS_CONTROL) to
 initiate system reboot/shutdown. At present OPAL queues IPMI messages
 and return SUCESS to Host. If BMC is not ready to accept command (like
 BMC reboot), then these message will fail. We have to manually
 reboot/shutdown the system using BMC interface.</p>
 <p>This patch adds logic to validate message return value. If message failed,
 then it will resend the message. At some stage BMC will be ready to accept
 message and handles IPMI message.</p>
 </li>
 <li><p>hw/bt: Add backend interface to disable ipmi message retry option</p>
 <p>During boot OPAL makes IPMI_GET_BT_CAPS call to BMC to get BT interface
 capabilities which includes IPMI message max resend count, message
 timeout, etc,. Most of the time OPAL gets response from BMC within
 specified timeout. In some corner cases (like mboxd daemon reset in BMC,
 BMC reboot, etc) OPAL may not get response within timeout period. In
 such scenarios, OPAL resends message until max resend count reaches.</p>
 <p>OPAL uses synchronous IPMI message (ipmi_queue_msg_sync()) for few
 operations like flash read, write, etc. Thread will wait in OPAL until
 it gets response from BMC. In some corner cases like BMC reboot, thread
 may wait in OPAL for long time (more than 20 seconds) and results in
 kernel hardlockup.</p>
 <p>This patch introduces new interface to disable message resend option. We
 will disable message resend option for synchrous message. This will
 greatly reduces kernel hardlock up issues.</p>
 <p>This is short term fix. Long term solution is to convert all synchronous
 messages to asynhrounous one.</p>
 </li>
 </ul>
 </section>
 <section id="phb3">
 <h2>PHB3<a class="headerlink" href="#phb3" title="Link to this heading">¶</a></h2>
 <ul>
 <li><p>hw/phb3/naples: Disable D-states</p>
 <p>Putting “Mellanox Technologies MT27700 Family [ConnectX-4] [15b3:1013]”
 (more precisely, the second of 2 its PCI functions, no matter in what
 order) into the D3 state causes EEH with the “PCT timeout” error.
 This has been noticed on garrison machines only and firestones do not
 seem to have this issue.</p>
 <p>This disables D-states changing for devices on root buses on Naples by
 installing a config space access filter (copied from PHB4).</p>
 </li>
 </ul>
 </section>
 </section>


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	<section id="skiboot-6-0-18">
	<span id="id1"></span><h1>skiboot-6.0.18<a class="headerlink" href="#skiboot-6-0-18" title="Link to this heading">¶</a></h1>
	<p>skiboot 6.0.18 was released on Wednesday March 6th, 2019. It replaces
	<a class="reference internal" href="skiboot-6.0.17.html#skiboot-6-0-17"><span class="std std-ref">skiboot-6.0.17</span></a> as the current stable release in the 6.0.x series.</p>
	<p>It is recommended that 6.0.18 be used instead of any previous 6.0.x version
	due to the bug fixes it contains.</p>
	<p>Over <a class="reference internal" href="skiboot-6.0.17.html#skiboot-6-0-17"><span class="std std-ref">skiboot-6.0.17</span></a> we have several bug fixes, including important ones
	for powercap, ipmi-hiomap and BMC communication driver.</p>
	<section id="powercap">
	<h2>powercap<a class="headerlink" href="#powercap" title="Link to this heading">¶</a></h2>
	<ul>
	<li><p>powercap: occ: Fix the powercapping range allowed for user</p>
	<p>OCC provides two limits for minimum powercap. One being hard powercap
	minimum which is guaranteed by OCC and the other one is a soft
	powercap minimum which is lesser than hard-min and may or may not be
	asserted due to various power-thermal reasons. So to allow the users
	to access the entire powercap range, this patch exports soft powercap
	minimum as the “powercap-min” DT property. And it also adds a new
	DT property called “powercap-hard-min” to export the hard-min powercap
	limit.</p>
	</li>
	</ul>
	</section>
	<section id="ipmi-hiomap">
	<h2>IPMI-HIOMAP<a class="headerlink" href="#ipmi-hiomap" title="Link to this heading">¶</a></h2>
	<ul>
	<li><p>ipmi-hiomap test case enhancements/fixes.</p></li>
	<li><p>libflash/ipmi-hiomap: Enforce message size for empty response</p>
	<p>The protocol defines the response to the associated messages as empty
	except for the command ID and sequence fields. If the BMC is returning
	extra data consider the message malformed.</p>
	</li>
	<li><p>libflash/ipmi-hiomap: Remove unused close handling</p>
	<p>Issuing a HIOMAP_C_CLOSE is not required by the protocol specification,
	rather a close can be implicit in a subsequent
	CREATE_{READ,WRITE}_WINDOW request. The implicit close provides an
	opportunity to reduce LPC traffic and the implementation takes up that
	optimisation, so remove the case from the IPMI callback handler.</p>
	</li>
	<li><p>libflash/ipmi-hiomap: Overhaul event handling</p>
	<p>Reworking the event handling was inspired by a bug report by Vasant
	where the host would get wedged on multiple flash access attempts in the
	face of a persistent error state on the BMC-side. The cause of this bug
	was the early-exit based on ctx->update, which erronously assumed that
	all events had been completely handled in prior calls to
	ipmi_hiomap_handle_events(). This is not true if e.g.
	HIOMAP_E_DAEMON_READY is clear in the prior calls.</p>
	<p>Regardless, there were other correctness and efficiency problems with
	the handling strategy:</p>
	<ul class="simple">
	<li><p>Ack-able event state was not restored in the face of errors in the
	process of re-establishing protocol state</p></li>
	<li><p>It forced needless window restoration with respect to the context in
	which ipmi_hiomap_handle_events() was called.</p></li>
	<li><p>Tests for HIOMAP_E_DAEMON_READY and HIOMAP_E_FLASH_LOST were redundant
	with the overhauled error handling introduced in the previous patch</p></li>
	</ul>
	<p>Fix all of the above issues and add comments to explain the event
	handling flow.</p>
	<p>Tests for correctness follow later in the series.</p>
	</li>
	<li><p>libflash/ipmi-hiomap: Overhaul error handling</p>
	<p>The aim is to improve the robustness with respect to absence of the
	BMC-side daemon. The current error handling roughly mirrors what was
	done for the mailbox implementation, but there’s room for improvement.</p>
	<p>Errors are split into two classes, those that affect the transport state
	and those that affect the window validity. From here, we push the
	transport state error checks right to the bottom of the stack, to ensure
	the link is known to be in a good state before any message is sent.
	Window validity tests remain as they were in the hiomap_window_move()
	and ipmi_hiomap_read() functions. Validity tests are not necessary in
	the write and erase paths as we will receive an error response from the
	BMC when performing a dirty or flush on an invalid window.</p>
	<p>Recovery also remains as it was, done on entry to the blocklevel
	callbacks. If an error state is encountered in the middle of an
	operation no attempt is made to recover it on the spot, instead the
	error is returned up the stack and the caller can choose how it wishes
	to respond.</p>
	</li>
	<li><p>libflash/ipmi-hiomap: Fix leak of msg in callback</p></li>
	</ul>
	</section>
	<section id="bmc-communication">
	<h2>BMC communication<a class="headerlink" href="#bmc-communication" title="Link to this heading">¶</a></h2>
	<ul>
	<li><p>core/ipmi: Add ipmi sync messages to top of the list</p>
	<p>In ipmi_queue_msg_sync() path OPAL will wait until it gets response from
	BMC. If we do not get response ontime we may endup in kernel hardlockups.
	Hence lets add sync messages to top of the queue. This will reduces the
	chance of hardlockups.</p>
	</li>
	<li><p>hw/bt: Introduce separate list for synchronous messages</p>
	<p>BT send logic always sends top of bt message list to BMC. Once BMC reads the
	message, it clears the interrupt and bt_idle() becomes true.</p>
	<p>bt_add_ipmi_msg_head() adds message to top of the list. If bt message list
	is not empty then:</p>
	<blockquote>
	<div><ul class="simple">
	<li><p>if bt_idle() is true then we will endup sending message to BMC before
	getting response from BMC for inflight message. Looks like on some
	BMC implementation this results in message timeout.</p></li>
	<li><p>else we endup starting message timer without actually sending message
	to BMC.. which is not correct.</p></li>
	</ul>
	</div></blockquote>
	<p>This patch introduces separate list to track synchronous messages.
	bt_add_ipmi_msg_head() will add messages to tail of this new list. We
	will always process this queue before processing normal queue.</p>
	<p>Finally this patch introduces new variable (inflight_bt_msg) to track
	inflight message. This will point to current inflight message.</p>
	</li>
	<li><p>hw/bt: Fix message retry handler</p>
	<p>In some corner cases (like BMC reboot), bt_send_and_unlock() starts
	message timer, but won’t send message to BMC as driver is not free to
	send message. bt_expire_old_msg() function enables H2B interrupt without
	actually sending message.</p>
	<p>This patch fixes above issue.</p>
	</li>
	<li><p>ipmi/power: Fix system reboot issue</p>
	<p>Kernel makes reboot/shudown OPAL call for reboot/shutdown. Once kernel
	gets response from OPAL it runs opal_poll_events() until firmware
	handles the request.</p>
	<p>On BMC based system, OPAL makes IPMI call (IPMI_CHASSIS_CONTROL) to
	initiate system reboot/shutdown. At present OPAL queues IPMI messages
	and return SUCESS to Host. If BMC is not ready to accept command (like
	BMC reboot), then these message will fail. We have to manually
	reboot/shutdown the system using BMC interface.</p>
	<p>This patch adds logic to validate message return value. If message failed,
	then it will resend the message. At some stage BMC will be ready to accept
	message and handles IPMI message.</p>
	</li>
	<li><p>hw/bt: Add backend interface to disable ipmi message retry option</p>
	<p>During boot OPAL makes IPMI_GET_BT_CAPS call to BMC to get BT interface
	capabilities which includes IPMI message max resend count, message
	timeout, etc,. Most of the time OPAL gets response from BMC within
	specified timeout. In some corner cases (like mboxd daemon reset in BMC,
	BMC reboot, etc) OPAL may not get response within timeout period. In
	such scenarios, OPAL resends message until max resend count reaches.</p>
	<p>OPAL uses synchronous IPMI message (ipmi_queue_msg_sync()) for few
	operations like flash read, write, etc. Thread will wait in OPAL until
	it gets response from BMC. In some corner cases like BMC reboot, thread
	may wait in OPAL for long time (more than 20 seconds) and results in
	kernel hardlockup.</p>
	<p>This patch introduces new interface to disable message resend option. We
	will disable message resend option for synchrous message. This will
	greatly reduces kernel hardlock up issues.</p>
	<p>This is short term fix. Long term solution is to convert all synchronous
	messages to asynhrounous one.</p>
	</li>
	</ul>
	</section>
	<section id="phb3">
	<h2>PHB3<a class="headerlink" href="#phb3" title="Link to this heading">¶</a></h2>
	<ul>
	<li><p>hw/phb3/naples: Disable D-states</p>
	<p>Putting “Mellanox Technologies MT27700 Family [ConnectX-4] [15b3:1013]”
	(more precisely, the second of 2 its PCI functions, no matter in what
	order) into the D3 state causes EEH with the “PCT timeout” error.
	This has been noticed on garrison machines only and firestones do not
	seem to have this issue.</p>
	<p>This disables D-states changing for devices on root buses on Naples by
	installing a config space access filter (copied from PHB4).</p>
	</li>
	</ul>
	</section>
	</section>


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