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author | Stewart Smith <stewart@linux.vnet.ibm.com> | 2017-10-11 19:48:28 +1100 |
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committer | Stewart Smith <stewart@linux.vnet.ibm.com> | 2017-10-11 19:48:44 +1100 |
commit | c29df9d7d8a97225f675337e7dd3f283520f6c21 (patch) | |
tree | 0ee5be83d991b03ba9e47df2ab3d56f5de002f00 /doc/release-notes | |
parent | d798c276b4da7559970702c2f31b12549c92741e (diff) | |
download | skiboot-c29df9d7d8a97225f675337e7dd3f283520f6c21.zip skiboot-c29df9d7d8a97225f675337e7dd3f283520f6c21.tar.gz skiboot-c29df9d7d8a97225f675337e7dd3f283520f6c21.tar.bz2 |
skiboot 5.4.8 release notes
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
(cherry picked from commit 43290f90e46d632ed5a314292c317e6f813c3b74)
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Diffstat (limited to 'doc/release-notes')
-rw-r--r-- | doc/release-notes/skiboot-5.4.8.rst | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/doc/release-notes/skiboot-5.4.8.rst b/doc/release-notes/skiboot-5.4.8.rst new file mode 100644 index 0000000..fa66085 --- /dev/null +++ b/doc/release-notes/skiboot-5.4.8.rst @@ -0,0 +1,158 @@ +.. _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. + |