Re: LinuxAsmTools Announcement

[Brian Raiter <breadbox@xxxxxxxxxxxxxx>]

> when i disassemble *.o object file on x86 machine and find
> instruction "call 0xFCFFFFFF",because not link,but why this address
> 0xFCFFFFFF not 0xFFFFFFFF or others?

First of all, the value is not 0xFCFFFFFF, it's 0xFFFFFFFC
(little-endian), which is the 32-bit equivalent of -4.

And the reason for the -4 is that it's an offset. When the linker
fills in the real address, it will subtract the subroutine's absolute
address from the address of the -4 value to get a relative address,
which it will then add to the existing -4 to get the correct relative
address for the call instruction. And, the reason that 4 needs to be
subtracted is that when the call is executed, it will actually jump
from the end of the call instruction, which is 4 bytes ahead of where
the relative address is stored.

b

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