Various x86 syscall mechanisms

From: Jeremy Fitzhardinge
Date: Fri Jun 20 2008 - 18:00:35 EST


Hi Roland,

As far as I can work out, an x86_32 kernel will use "int 0x80" and "sysenter" for system calls. 64-bit kernel will use just "syscall" for 64-bit processes (though you can use "int 0x80" to access the 32-bit syscall interface from a 64-bit process), but will allow "sysenter", "syscall" or "int 0x80" for 32-on-64 processes.

Why does 32-on-64 implement 32-bit syscall when native 32-bit doesn't seem to? Or am I overlooking something here? Does 32-bit also support syscall?

Thanks,
J
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