From: John Donnelly <hidden> Date: 2014-02-14 20:42:28
Hi,
I tried using the SysRq hotkey sequence on a serial console -
3.11.0-5-powerpc-e500mc system, by issuing a " break " and the system
immediately wedges after displaying "SysRQ : HELP : " using both "Putty"
and "Teraterm" terminal emulators. I know the system is dead because my
ssh sessions stopped too.
http://en.wikipedia.org/wiki/Magic_SysRq_key .
--
*Regards,*
* John.*
*--*
*o* Energy-efficiency is #1 reason data centers look to expand. -- Digital
Realty Trust
*o* Green Data Centers spending to increase 300% worldwide by 2016. --
Pike Research
*o *Data Centers have become as vital to the functioni
ng of society as power stations. -- The Economist
From: Paul Gortmaker <hidden> Date: 2014-02-16 15:57:01
On Fri, Feb 14, 2014 at 3:42 PM, John Donnelly [off-list ref] wrote:
Hi,
I tried using the SysRq hotkey sequence on a serial console -
3.11.0-5-powerpc-e500mc system, by issuing a " break " and the system
immediately wedges after displaying "SysRQ : HELP : " using both "Putty" and
"Teraterm" terminal emulators. I know the system is dead because my ssh
sessions stopped too.
Yes it does work -- or at least it _did_ work. Make sure your dts has an entry
compatible = "fsl,ns16550", "ns16550";
since that enables a workaround I'd added for a hardware errata relating
to sending breaks over the serial console. What you describe above
makes me think you aren't getting the workaround enabled.
Paul.
--
http://en.wikipedia.org/wiki/Magic_SysRq_key .
--
Regards,
John.
--
o Energy-efficiency is #1 reason data centers look to expand. -- Digital
Realty Trust
o Green Data Centers spending to increase 300% worldwide by 2016. -- Pike
Research
o Data Centers have become as vital to the functioni
ng of society as power stations. -- The Economist
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Linuxppc-dev@lists.ozlabs.org
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From: Scott Wood <hidden> Date: 2014-02-17 19:37:14
On Sun, 2014-02-16 at 10:56 -0500, Paul Gortmaker wrote:
On Fri, Feb 14, 2014 at 3:42 PM, John Donnelly [off-list ref] wrote:
quoted
Hi,
I tried using the SysRq hotkey sequence on a serial console -
3.11.0-5-powerpc-e500mc system, by issuing a " break " and the system
immediately wedges after displaying "SysRQ : HELP : " using both "Putty" and
"Teraterm" terminal emulators. I know the system is dead because my ssh
sessions stopped too.
Yes it does work -- or at least it _did_ work. Make sure your dts has an entry
compatible = "fsl,ns16550", "ns16550";
since that enables a workaround I'd added for a hardware errata relating
to sending breaks over the serial console. What you describe above
makes me think you aren't getting the workaround enabled.
Also make sure CONFIG_SERIAL_8250_FSL is enabled.
-Scott
From: John Donnelly <hidden> Date: 2014-02-18 19:47:57
I am enable to get one keyboard sequence responded to with the noted change
in the dts .
for instance:
SysRQ ( Break) c
Panics .. Which is a good response, and since it doesn't require a return
to user mode ( I suspect ) it appears to work.
Any other requests fail to report any information :
SysRQ (break ) l - list active processes
m - list memory
Any additional SysRQ are ignored., and the system appears hung.
On an reference Intel platform, multiple SyqRQ can be issued and the
system remains healthy .
On Mon, Feb 17, 2014 at 1:37 PM, Scott Wood [off-list ref] wrote:
On Sun, 2014-02-16 at 10:56 -0500, Paul Gortmaker wrote:
quoted
On Fri, Feb 14, 2014 at 3:42 PM, John Donnelly [off-list ref]
wrote:
quoted
quoted
Hi,
I tried using the SysRq hotkey sequence on a serial console -
3.11.0-5-powerpc-e500mc system, by issuing a " break " and the system
immediately wedges after displaying "SysRQ : HELP : " using both
"Putty" and
quoted
quoted
"Teraterm" terminal emulators. I know the system is dead because my
ssh
quoted
quoted
sessions stopped too.
Yes it does work -- or at least it _did_ work. Make sure your dts has
an entry
quoted
compatible = "fsl,ns16550", "ns16550";
since that enables a workaround I'd added for a hardware errata relating
to sending breaks over the serial console. What you describe above
makes me think you aren't getting the workaround enabled.
Also make sure CONFIG_SERIAL_8250_FSL is enabled.
-Scott
--
*Regards,*
* John.*
*--*
*o* Energy-efficiency is #1 reason data centers look to expand. -- Digital
Realty Trust
*o* Green Data Centers spending to increase 300% worldwide by 2016. --
Pike Research
*o *Data Centers have become as vital to the functioni
ng of society as power stations. -- The Economist
From: Paul Gortmaker <hidden> Date: 2014-02-19 18:41:50
[BTW, your html mail may be ignored by most people ; for example most of
the linux lists on vger.kernel.org actively reject it; top posting isn't
going to help either... ]
On 14-02-18 02:47 PM, John Donnelly wrote:
I am enable to get one keyboard sequence responded to with the noted change
in the dts .
for instance:
SysRQ ( Break) c
Panics .. Which is a good response, and since it doesn't require a return
to user mode ( I suspect ) it appears to work.
Any other requests fail to report any information :
SysRQ (break ) l - list active processes
m - list memory
Any additional SysRQ are ignored., and the system appears hung.
It must be something specific about your particular platform, or the
custom patches you have applied then. I just tested today's linux-next
tree (i.e. the latest bleeding edge stuff) and it still works for the
sbc8548 (defconfig + enable magic SYSRQ option). I did "s" (sync) multiple
times and "?" then "m" for memory dump (obviously those chars don't get
echo'd to the console....
---------------------------------------
root@sbc8548:~# cat /proc/cpuinfo |grep cpu
cpu : e500v2
root@sbc8548:~# SysRq : Emergency Sync
Emergency Sync complete
SysRq : Emergency Sync
Emergency Sync complete
SysRq : HELP : loglevel(0-9) reboot(b) crash(c) terminate-all-tasks(e) memory-full-oom-kill(f) kill-all-tasks(i) thaw-filesystems(j) show-memory-usage(m) nice-all-RT-tasks(n) poweroff(o) show-registers(p) show-all-timers(q) sync(s) show-task-states(t) unmount(u) show-blocked-tasks(w)
SysRq : Show Memory
Mem-Info:
DMA per-cpu:
CPU 0: hi: 186, btch: 31 usd: 132
active_anon:738 inactive_anon:29 isolated_anon:0
active_file:915 inactive_file:2219 isolated_file:0
unevictable:0 dirty:0 writeback:0 unstable:0
free:188325 slab_reclaimable:488 slab_unreclaimable:778
mapped:1006 shmem:44 pagetables:83 bounce:0
free_cma:0
DMA free:753300kB min:3520kB low:4400kB high:5280kB active_anon:2952kB inactive_anon:116kB active_file:3660kB inactive_file:8876kB unevictable:0kB isolated(anon):0kB isolated(file):0kB
present:786432kB managed:775916kB mlocked:0kB dirty:0kB writeback:0kB mapped:4024kB shmem:176kB slab_reclaimable:1952kB slab_unreclaimable:3112kB kernel_stack:264kB pagetables:332kB uns
table:0kB bounce:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no
lowmem_reserve[]: 0 0 0
DMA: 403*4kB (UEM) 271*8kB (UEM) 131*16kB (UM) 35*32kB (UM) 15*64kB (UEM) 1*128kB (M) 1*256kB (M) 1*512kB (U) 1*1024kB (U) 3*2048kB (UEM) 180*4096kB (MR) = 753300kB
3178 total pagecache pages
0 pages in swap cache
Swap cache stats: add 0, delete 0, find 0/0
Free swap = 0kB
Total swap = 0kB
196608 pages RAM
0 pages HighMem/MovableOnly
2629 pages reserved
---------------------------------------
Paul.
--
On an reference Intel platform, multiple SyqRQ can be issued and the
system remains healthy .
On Mon, Feb 17, 2014 at 1:37 PM, Scott Wood [off-list ref] wrote:
quoted
On Sun, 2014-02-16 at 10:56 -0500, Paul Gortmaker wrote:
quoted
On Fri, Feb 14, 2014 at 3:42 PM, John Donnelly [off-list ref]
wrote:
quoted
quoted
Hi,
I tried using the SysRq hotkey sequence on a serial console -
3.11.0-5-powerpc-e500mc system, by issuing a " break " and the system
immediately wedges after displaying "SysRQ : HELP : " using both
"Putty" and
quoted
quoted
"Teraterm" terminal emulators. I know the system is dead because my
ssh
quoted
quoted
sessions stopped too.
Yes it does work -- or at least it _did_ work. Make sure your dts has
an entry
quoted
compatible = "fsl,ns16550", "ns16550";
since that enables a workaround I'd added for a hardware errata relating
to sending breaks over the serial console. What you describe above
makes me think you aren't getting the workaround enabled.
Also make sure CONFIG_SERIAL_8250_FSL is enabled.
-Scott