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authorLinus Torvalds <torvalds@linux-foundation.org>2013-07-10 10:10:02 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-10 10:10:02 -0700
commitb247759642cc96a75122907cc898b4c43b4f86ce (patch)
tree568e6ab08f2b986ff0b1ef80318c6c56c5d2ef42 /Documentation
parent61e312914cc82c085c945f88e5a53d507dd7d0d4 (diff)
parent5b879d78bc0818aa710f5d4d9abbfc2aca075cc3 (diff)
Merge branch 'parisc-for-3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux
Pull parisc updates from Helge Deller: "The PA-RISC updates for v3.11 include a gcc miscompilation fix, gzip-compressed vmlinuz support, a fix in the PCI code for ATI FireGL support on c8000 machines, a fix to prevent that %sr1 is being clobbered and a few smaller optimizations and documentation updates" * 'parisc-for-3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux: parisc: Fix gcc miscompilation in pa_memcpy() parisc: Ensure volatile space register %sr1 is not clobbered parisc: optimize mtsp(0,sr) inline assembly parisc: switch to gzip-compressed vmlinuz kernel parisc: document the shadow registers parisc: more capabilities info in /proc/cpuinfo parisc: fix LMMIO mismatch between PAT length and MASK register
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/parisc/registers8
1 files changed, 8 insertions, 0 deletions
diff --git a/Documentation/parisc/registers b/Documentation/parisc/registers
index dd3caddd1ad9..10c7d1730f5d 100644
--- a/Documentation/parisc/registers
+++ b/Documentation/parisc/registers
@@ -78,6 +78,14 @@ Shadow Registers used by interruption handler code
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.