提交 a83f58bc 编写于 作者: H Helge Deller

parisc: document the shadow registers

Signed-off-by: NHelge Deller <deller@gmx.de>
Cc: <stable@vger.kernel.org> # 3.10
上级 30a9f0b2
...@@ -77,6 +77,14 @@ PSW default E value 0 ...@@ -77,6 +77,14 @@ PSW default E value 0
Shadow Registers used by interruption handler code Shadow Registers used by interruption handler code
TOC enable bit 1 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 Register usage notes, originally from John Marvin, with some additional
notes from Randolph Chung. notes from Randolph Chung.
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