From owner-freebsd-hackers Tue Jun 30 13:16:50 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id NAA26373 for freebsd-hackers-outgoing; Tue, 30 Jun 1998 13:16:50 -0700 (PDT) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from bingsun2 (bingsun2.cc.binghamton.edu [128.226.1.6]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id NAA26335 for ; Tue, 30 Jun 1998 13:16:42 -0700 (PDT) (envelope-from bf20761@binghamton.edu) Received: from localhost (bf20761@localhost) by bingsun2 (SMI-8.6/8.6.9) with SMTP id QAA11387 for ; Tue, 30 Jun 1998 16:16:40 -0400 Date: Tue, 30 Jun 1998 16:16:39 -0400 (EDT) From: zhihuizhang X-Sender: bf20761@bingsun2 To: hackers Subject: Trap types and AST Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG I am trying to trace down how the vm_fault() gets called via trap mechanism and I find something do not understand: (1) The value of T_PAGEFLT is 12 not 14. Why trap type definitions in trap.h do not conform to the trap numbers defined in 80386 hardware terminology (one more example is T_NMI which is defined as 19 not 2). (2) The setidt() in file machdep.c set the DPL for page fault as SEL_KPL. This will prevent a normal process from handling page fault, only kernel process can. Why is the case? (this question requires the understanding of gate descriptors). (3) I come across many occurrences of AST, such as SWI_AST_MASK. Clearly, AST does not stand for the PC manufacturer here. I read in Mailing list that AST is an event. Can anyone tell me what does AST stand for and how it is used? Thanks in advance. ------------------------------------------------- Zhihui Zhang Department of Computer Science State University of New York at Binghamton Web Site: http://cs.binghamton.edu/~zzhang ------------------------------------------------- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message