Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [ 21/72] parisc: document the shadow registers | Date | Thu, 18 Jul 2013 22:25:38 -0700 |
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3.10-stable review patch. If anyone has any objections, please let me know.
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From: Helge Deller <deller@gmx.de>
commit a83f58bcb24003b9de2364de7c829a263423ead7 upstream.
Signed-off-by: Helge Deller <deller@gmx.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- Documentation/parisc/registers | 8 ++++++++ 1 file changed, 8 insertions(+)
--- a/Documentation/parisc/registers +++ b/Documentation/parisc/registers @@ -78,6 +78,14 @@ Shadow Registers used by interruption h TOC enable bit 1 ========================================================================= + +The PA-RISC architecture defines 7 registers as "shadow registers". +Those are used in RETURN FROM INTERRUPTION AND RESTORE instruction to reduce +the state save and restore time by eliminating the need for general register +(GR) saves and restores in interruption handlers. +Shadow registers are the GRs 1, 8, 9, 16, 17, 24, and 25. + +========================================================================= Register usage notes, originally from John Marvin, with some additional notes from Randolph Chung.
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