Date: Wed, 10 Sep 1997 18:16:45 -0700 (PDT) From: Sean Eric Fagan <sef@Kithrup.COM> To: grog@lemis.com Cc: emulation@FreeBSD.ORG Subject: Re: Net posting: SCO gets Linux emulation Message-ID: <199709110116.SAA09679@kithrup.com>
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>> I looked at the program; it's interesting, but not terribly exciting. >> However, I might have done the iBCS2 emulation the same way, if I could >> have -- however, trapping the system call vector in a user-mode program is >> hard. If 386BSD had used a different entry vector... >It's a question of performance. If I understand it correctly, you do >a SIGSEGV for every system call. That is a problem. It takes something like three system calls for every single Linux system call. (I am counting signal delivery as equivalent to a system call; in practice, it may be a bit higher.) For syscall-intensive programs, this is a lot of overhead, and is a known limitation. However, not running at all is also quite a lot of overhead :). Sean.
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