Re: [PATCH v3 0/4] sparc64: Jump to boot prom from console on panic

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On 2/1/2017 1:50 PM, David Miller wrote:
From: Vijay Kumar <vijay.ac.kumar@xxxxxxxxxx>
Date: Wed,  1 Feb 2017 11:34:36 -0800

Currently Stop-A (L1A) does not make the kernel switch to OBP on panic.
This is intentional, the kernel prints a message telling the user to
press break (L1-A) if they want to drop out of the kernel and we force
the break to be allowed by setting stop_a_enabled.
The problem is that pressing BRK after panic does not drop to OK prompt (when stop_a_enabled is set). So the kernel message to press Stop-A to return to boot
prom is  misleading in this case.
I'm wondering why there is so much effort being directed into BRK
behavior.
User can drop into ok prompt from the running kernel and as well as from the
panicked kernel. Pressing single break to jump to ok prompt conflicts with
sysrq key combination (from console, BRK + sysrq_key). To be consistent
across both the cases,  user will have to send BRK twice in order to drop to
ok prompt.  Does this sound reasonable?

If you want to break into the OK prompt, have the reboot-cmd
environment variable set appropriately, and simply hit BRK and it will
work in both ldom and non-ldom environments.
Kernel does not print message "Press Stop-A (L1-A) to ..." for the case when it is expected to reboot on panic. Rather, it goes through different path in panic() when
kernel.panic is _not_ set to 0. Here, patch is addressing the case when
kernel.panic=0 (i.e not to reboot on panic).

Thanks,
Vijay
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