Re: [PATCH 9/9] ttyFDC: Implement KGDB IO operations.

[Greg Kroah-Hartman]

On Thu, Jan 29, 2015 at 11:14:14AM +0000, James Hogan wrote:
> Implement KGDB IO operations for MIPS Fast Debug Channel (FDC). This can
> be enabled via Kconfig, which also allows the channel number to be
> chosen.
> 
> The magic sysrq hack is implemented in the TTY driver, detecting just ^C
> for the KGDB channel, and ^O followed by a letter for the FDC console
> channel.
> 
> The KGDB operations are reasonably efficient thanks to the flush
> callback, with a 4 byte buffer being used in both directions to allow up
> to 4 bytes to be encoded per FDC word. Reading of data for KGDB will
> discard any data received on other channels, which clearly isn't ideal,
> but given that there is a single FIFO shared between channels we can't
> do much better.
> 
> Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx>
> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: Jiri Slaby <jslaby@xxxxxxx>
> Cc: Jason Wessel <jason.wessel@xxxxxxxxxxxxx>
> Cc: linux-mips@xxxxxxxxxxxxxx
> Cc: kgdb-bugreport@xxxxxxxxxxxxxxxxxxxxx

Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
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