From: Vijay Kumar <vijay.ac.kumar@oracle.com> To: David Miller <davem@davemloft.net> Cc: sparclinux@vger.kernel.org, karl.volz@oracle.com, rob.gardner@oracle.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 0/4] sparc64: Jump to boot prom from console on panic Date: Wed, 1 Feb 2017 15:20:08 -0600 [thread overview] Message-ID: <271b7e7c-5e2f-eab6-d097-54145b777d73@oracle.com> (raw) In-Reply-To: <20170201.145031.295104986575080480.davem@davemloft.net> On 2/1/2017 1:50 PM, David Miller wrote: > From: Vijay Kumar <vijay.ac.kumar@oracle.com> > 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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From: Vijay Kumar <vijay.ac.kumar@oracle.com> To: David Miller <davem@davemloft.net> Cc: sparclinux@vger.kernel.org, karl.volz@oracle.com, rob.gardner@oracle.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 0/4] sparc64: Jump to boot prom from console on panic Date: Wed, 01 Feb 2017 21:20:08 +0000 [thread overview] Message-ID: <271b7e7c-5e2f-eab6-d097-54145b777d73@oracle.com> (raw) In-Reply-To: <20170201.145031.295104986575080480.davem@davemloft.net> On 2/1/2017 1:50 PM, David Miller wrote: > From: Vijay Kumar <vijay.ac.kumar@oracle.com> > 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
next prev parent reply other threads:[~2017-02-01 21:20 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-02-01 19:34 [PATCH v3 0/4] sparc64: Jump to boot prom from console on panic Vijay Kumar 2017-02-01 19:34 ` Vijay Kumar 2017-02-01 19:34 ` [PATCH v3 1/4] sparc64: Set cpu state to offline when stopped Vijay Kumar 2017-02-01 19:34 ` Vijay Kumar 2017-02-01 19:34 ` [PATCH v3 2/4] sparc64: Migrate hvcons irq to panicked cpu Vijay Kumar 2017-02-01 19:34 ` Vijay Kumar 2017-02-01 19:34 ` [PATCH v3 3/4] sparc64: Send break twice from console to return to boot prom Vijay Kumar 2017-02-01 19:34 ` Vijay Kumar 2017-02-01 19:34 ` [PATCH v3 4/4] Documentation/sparc: Steps for sending break on sunhv console Vijay Kumar 2017-02-01 19:34 ` Vijay Kumar 2017-02-01 19:50 ` [PATCH v3 0/4] sparc64: Jump to boot prom from console on panic David Miller 2017-02-01 19:50 ` David Miller 2017-02-01 21:20 ` Vijay Kumar [this message] 2017-02-01 21:20 ` Vijay Kumar 2017-02-23 16:27 ` David Miller 2017-02-23 16:27 ` David Miller
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