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Hi there guys,
I have another asm question to rack your brains :)
code excerpt:
<from include/asm-i396/system.h:300>
300 #define alternative(oldinstr, newinstr, feature) \
301 asm volatile ("661:\n\t" oldinstr "\n662:\n" \
302 ".section .altinstructions,\"a\"\n" \
303 " .align 4\n" \
304 " .long 661b\n" /* label */ \
305 " .long 663f\n" /* new instruction */
\
306 " .byte %c0\n" /* feature bit */ \
307 " .byte 662b-661b\n" /* sourcelen */ \
308 " .byte 664f-663f\n" /* replacementlen */ \
309 ".previous\n"
\
310 ".section .altinstr_replacement,\"ax\"\n"
\
311 "663:\n\t" newinstr "\n664:\n" /* replacement */
\
312 ".previous" :: "i" (feature) : "memory")
What is does the ".previous" directive do? I see that it is being used
extensively in kernel asm code but i could only guess (maybe is a some kind
of program control redirection instruction but this is pretty vague and not
sure). It isn't mentioned in the GAS manual so maybe it is something
magical? :))
TIA,
Boris.
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