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List:       linux-kernel
Subject:    Re: [patch] fastcall-2.3.32-B6, SYSENTER/SYSEXIT support
From:       Richard Gooch <rgooch () ras ! ucalgary ! ca>
Date:       1999-12-12 19:16:39
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Ulrich Drepper writes:
> Richard Gooch <rgooch@ras.ucalgary.ca> writes:
> 
> > > > I propose a much simpler abstraction: set up a global page (which
> > > > always appears at a fixed address in user-space), and set up a jump
> > > > table. Have one jump vector per system call. That's the ABI. End of
> > > > story.
> > > 
> > > I really like that.
> > 
> > Thanks.
> 
> This introduces major problems.  What about libraries/programs which
> make syscalls which are not available on the system?  The libc
> relies on unimplemented syscalls return ENOSYS.

Populate the jump table with trailing entries which return ENOSYS.

Alternatively, the kernel writes the number of syscalls at the end of
the global page. The libc syscall interface then checks this value
against the syscall number.

				Regards,

					Richard....
Permanent: rgooch@atnf.csiro.au
Current:   rgooch@ras.ucalgary.ca


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