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authorStewart Smith <stewart@linux.vnet.ibm.com>2017-10-11 19:48:28 +1100
committerStewart Smith <stewart@linux.vnet.ibm.com>2017-10-11 19:48:28 +1100
commit43290f90e46d632ed5a314292c317e6f813c3b74 (patch)
tree2505ec024c86fb09e41bd1b261aa7b505beb3de4
parent374fde2777647b8f78347c749630fb81d35bae24 (diff)
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skiboot 5.4.8 release notesskiboot-5.4.8
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
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+.. _skiboot-5.4.8:
+
+=============
+skiboot-5.4.8
+=============
+
+skiboot-5.4.8 was released on Wednesday October 11th, 2017. It replaces
+:ref:`skiboot-5.4.7` as the current stable release in the 5.4.x series.
+
+Over :ref:`skiboot-5.4.7`, we have a few bug fixes for FSP platforms:
+
+- libflash/file: Handle short read()s and write()s correctly
+
+ Currently we don't move the buffer along for a short read() or write()
+ and nor do we request only the remaining amount.
+- FSP/NVRAM: Handle "get vNVRAM statistics" command
+
+ FSP sends MBOX command (cmd : 0xEB, subcmd : 0x05, mod : 0x00) to get vNVRAM
+ statistics. OPAL doesn't maintain any such statistics. Hence return
+ FSP_STATUS_INVALID_SUBCMD.
+
+ Sample OPAL log: ::
+
+ [16944.384670488,3] FSP: Unhandled message eb0500
+ [16944.474110465,3] FSP: Unhandled message eb0500
+ [16945.111280784,3] FSP: Unhandled message eb0500
+ [16945.293393485,3] FSP: Unhandled message eb0500
+- FSP/CONSOLE: Limit number of error logging
+
+ Commit c8a7535f (FSP/CONSOLE: Workaround for unresponsive ipmi daemon, added
+ in skiboot 5.4.6 and 5.7-rc1) added error logging when buffer is full. In some
+ corner cases kernel may call this function multiple time and we may endup logging
+ error again and again.
+
+ This patch fixes it by generating error log only once.
+
+- FSP/CONSOLE: Fix fsp_console_write_buffer_space() call
+
+ Kernel calls fsp_console_write_buffer_space() to check console buffer space
+ availability. If there is enough buffer space to write data, then kernel will
+ call fsp_console_write() to write actual data.
+
+ In some extreme corner cases (like one explained in commit c8a7535f)
+ console becomes full and this function returns 0 to kernel (or space available
+ in console buffer < next incoming data size). Kernel will continue retrying
+ until it gets enough space. So we will start seeing RCU stalls.
+
+ This patch keeps track of previous available space. If previous space is same
+ as current means not enough space in console buffer to write incoming data.
+ It may be due to very high console write operation and slow response from FSP
+ -OR- FSP has stopped processing data (ex: because of ipmi daemon died). At this
+ point we will start timer with timeout of SER_BUFFER_OUT_TIMEOUT (10 secs).
+ If situation is not improved within 10 seconds means something went bad. Lets
+ return OPAL_RESOURCE so that kernel can drop console write and continue.
+- FSP/CONSOLE: Close SOL session during R/R
+
+ Presently we are not closing SOL and FW console sessions during R/R. Host will
+ continue to write to SOL buffer during FSP R/R. If there is heavy console write
+ operation happening during FSP R/R (like running `top` command inside console),
+ then at some point console buffer becomes full. fsp_console_write_buffer_space()
+ returns 0 (or less than required space to write data) to host. While one thread
+ is busy writing to console, if some other threads tries to write data to console
+ we may see RCU stalls (like below) in kernel.
+
+ kernel call trace: ::
+
+ [ 2082.828363] INFO: rcu_sched detected stalls on CPUs/tasks: { 32} (detected by 16, t=6002 jiffies, g=23154, c=23153, q=254769)
+ [ 2082.828365] Task dump for CPU 32:
+ [ 2082.828368] kworker/32:3 R running task 0 4637 2 0x00000884
+ [ 2082.828375] Workqueue: events dump_work_fn
+ [ 2082.828376] Call Trace:
+ [ 2082.828382] [c000000f1633fa00] [c00000000013b6b0] console_unlock+0x570/0x600 (unreliable)
+ [ 2082.828384] [c000000f1633fae0] [c00000000013ba34] vprintk_emit+0x2f4/0x5c0
+ [ 2082.828389] [c000000f1633fb60] [c00000000099e644] printk+0x84/0x98
+ [ 2082.828391] [c000000f1633fb90] [c0000000000851a8] dump_work_fn+0x238/0x250
+ [ 2082.828394] [c000000f1633fc60] [c0000000000ecb98] process_one_work+0x198/0x4b0
+ [ 2082.828396] [c000000f1633fcf0] [c0000000000ed3dc] worker_thread+0x18c/0x5a0
+ [ 2082.828399] [c000000f1633fd80] [c0000000000f4650] kthread+0x110/0x130
+ [ 2082.828403] [c000000f1633fe30] [c000000000009674] ret_from_kernel_thread+0x5c/0x68
+
+ Hence lets close SOL (and FW console) during FSP R/R.
+
+- FSP/CONSOLE: Do not associate unavailable console
+
+ Presently OPAL sends associate/unassociate MBOX command for all
+ FSP serial console (like below OPAL message). We have to check
+ console is available or not before sending this message.
+
+ OPAL log: ::
+
+ [ 5013.227994012,7] FSP: Reassociating HVSI console 1
+ [ 5013.227997540,7] FSP: Reassociating HVSI console 2
+- FSP: Disable PSI link whenever FSP tells OPAL about impending Reset/Reload
+
+ Commit 42d5d047 fixed scenario where DPO has been initiated, but FSP went
+ into reset before the CEC power down came in. But this is generic issue
+ that can happen in normal shutdown path as well.
+
+ Hence disable PSI link as soon as we detect FSP impending R/R.
+
+
+- fsp: return OPAL_BUSY_EVENT on failure sending FSP_CMD_POWERDOWN_NORM
+ Also, return OPAL_BUSY_EVENT on failure sending FSP_CMD_REBOOT / DEEP_REBOOT.
+
+ We had a race condition between FSP Reset/Reload and powering down
+ the system from the host:
+
+ Roughly:
+
+ == ======================== ==========================================================
+ # FSP Host
+ == ======================== ==========================================================
+ 1 Power on
+ 2 Power on
+ 3 (inject EPOW)
+ 4 (trigger FSP R/R)
+ 5 Processes EPOW event, starts shutting down
+ 6 calls OPAL_CEC_POWER_DOWN
+ 7 (is still in R/R)
+ 8 gets OPAL_INTERNAL_ERROR, spins in opal_poll_events
+ 9 (FSP comes back)
+ 10 spinning in opal_poll_events
+ 11 (thinks host is running)
+ == ======================== ==========================================================
+
+ The call to OPAL_CEC_POWER_DOWN is only made once as the reset/reload
+ error path for fsp_sync_msg() is to return -1, which means we give
+ the OS OPAL_INTERNAL_ERROR, which is fine, except that our own API
+ docs give us the opportunity to return OPAL_BUSY when trying again
+ later may be successful, and we're ambiguous as to if you should retry
+ on OPAL_INTERNAL_ERROR.
+
+ For reference, the linux code looks like this: ::
+
+ static void __noreturn pnv_power_off(void)
+ {
+ long rc = OPAL_BUSY;
+
+ pnv_prepare_going_down();
+
+ while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
+ rc = opal_cec_power_down(0);
+ if (rc == OPAL_BUSY_EVENT)
+ opal_poll_events(NULL);
+ else
+ mdelay(10);
+ }
+ for (;;)
+ opal_poll_events(NULL);
+ }
+
+ Which means that *practically* our only option is to return OPAL_BUSY
+ or OPAL_BUSY_EVENT.
+
+ We choose OPAL_BUSY_EVENT for FSP systems as we do want to ensure we're
+ running pollers to communicate with the FSP and do the final bits of
+ Reset/Reload handling before we power off the system.
+