Compiler warning when compiling 2.6.32-rc5 as follows:
AS arch/alpha/kernel/entry.o
arch/alpha/kernel/entry.S: Assembler messages:
arch/alpha/kernel/entry.S:326: Warning: operand out of range
(0x0000000000000406 is not between 0x0000000000000000 and
0x00000000000000ff)
arch/alpha/kernel/entry.S:388: Warning: operand out of range
(0x0000000000000406 is not between 0x0000000000000000 and
0x00000000000000ff)
One offending line (326) is:
and $5, _TIF_WORK_MASK, $2
The warning occurs because commit d0420c83f39f "KEYS: Extend
TIF_NOTIFY_RESUME to (almost) all architectures [try #6]" introduces
TIF_NOTIFIY_RESUME which sets bit 10 in _TIF_WORK_MASK (see
arch/alpha/include/asm/thread_info.h) but _TIF_WORK_MASK is used in the
immediate addressing mode in the assembler instruction above. The 'and'
instruction can only take an immediate datum in the range 0 to 255. With
the addition of the TIF_NOTIFY_RESUME bit, _TIF_WORK_MASK is no longer in
the valid range for immediate addressing in the 'and' instruction.
On the assumption that it is important to include the TIF_NOTIFY_RESUME bit
one might be tempted to modify the code to:
lda $2, _TIF_WORK_MASK
and $5, $2, $2
but this is time critical code. I am wondering whether it might be better
to rearrange the bits in the thread information flags so that _TIF_WORK_MASK
has a value less than 255 and the single instruction to perform an and
operation can be maintained.
Comments?
Cheers
Michael.
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