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SubjectRe: Differences between FreeBSD and Linux system call mechanism
On Thu, Sep 03, 1998 at 02:47:10PM +0100, Alan Cox wrote:
> > 1) Linux system calls are done using software interrupt 0x80 on ia32.
> > Does this qualify as a "call-gate based kernel entry"?
> No. Call gates are a paticular intel mechanism for jumping between rings
> (priviledge levels). You can see an example of this in the iBCS2 handlers
> since iBCS uses call gates. An int based call is faster, and sysenter
> is potentially faster still but sysenter is only on some later PII chips

Doesn't this mean that it would be a good idea to let the kernel
implement system calls by mapping a page into user-space containing
the appropriate assembly instructions to most efficiently do the
system calls?


Alexander Kjeldaas, Guardian Networks AS, Trondheim, Norway

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