Stewart Smith stewart at linux.vnet.ibm.com
Tue Jan 12 15:15:00 AEDT 2016

Russell Currey <ruscur at russell.cc> writes:

> uart consoles only flush output when polled.  The Linux kernel calls
> these pollers frequently, except when in a panic state.  As such, panic
> messages are not fully printed unless the system is configured to reboot
> after panic.
> This patch adds a new call to the OPAL API to flush the buffer.  If the
> system has a uart console (i.e. BMC machines), it will incrementally
> flush the buffer, returning if there is more to be flushed or not.  If
> the system has a different console, the function will have no effect.
> This will allow the Linux kernel to ensure that panic message have been
> fully printed out.
> The existing synchronous flushing mechanism used in OPAL's shutdown and
> reboot routines has been refactored into a helper that repeatedly calls
> the new partial flush function.
> Signed-off-by: Russell Currey <ruscur at russell.cc>
> ---
> Changes since V1:
>  - Refactored into a partial flush instead of a full synchronous flush
>  - Added different return values based on the status
>  - Change the synchronous flushing function to use the new call
> This patch is dependent on being merged before the PCI hotplug patches,
> which also add a new OPAL API call, incrementing OPAL_LAST.
> This should eventually head towards stable, maybe only after the kernel
> patch that uses it gets merged?


Merged to stable as of f2efc65 and master as of 0890821.

Note that we still need the kernel patch to match this.

Stewart Smith
OPAL Architect, IBM.

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