Please help: question about inline ASM in local_bh_enable

Lei Luo <lluo@eecis.udel.edu> · Fri, 02 Apr 2004 12:04:20 -0500

Hi,

I have a question about the inline assembly in local_bh_enable, which is 
in asm-i386/softirq.h.

       .....

       "2: pushl %%eax; pushl %%ecx; pushl %%edx;"     \

       "call %c1;"                                     \

                 ^^^

        .....                                                   \

: /* no output */                                       \

: "r" (ptr), "i" (do_softirq)                           \

/* no registers clobbered */ );                         \

I don't understand why it uses "call %c1" instead of "call %1". I 
searched some online tutorials about inline assembly, but none of them 
mentioned this. I wrote a small test code to try it and it works. Is it 
a special syntax for "call"? Can someone give an explanation?

Thanks so much!

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