[SeaBIOS] How "_cfuncXX_" symbol prefix is added ?

[wx]

Sorry for previous wrong mail Title~~

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hi,kevin
    there is patch  from 0.6.1 to 0.6.2 
    f3fe3aa7a0ccb881e659a4281d6f0a0bb5c33cc5 (Require a "_cfuncXX_" symbol prefix for inter-mode c function references.)

how _cfunc32flat_, _cfunc32seg_ prefix are added to C function symbols ?
    It seems that macro "VISIBLE32FLAT" or "VISIBLE32SEG" can not do this or which gcc attributes influence it  ?
        post.c
           void VISIBLE32FLAT
            _start(void)
            {
        romleyout.S
            _cfunc32flat__start

thanks!
wx