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Path: sserve!newshost.anu.edu.au!munnari.oz.au!constellation!osuunx.ucc.okstate.edu!moe.ksu.ksu.edu!zaphod.mps.ohio-state.edu!cs.utexas.edu!uunet!news.univie.ac.at!fstgds15.tu-graz.ac.at!fstgds01.tu-graz.ac.at!not-for-mail From: chmr@edvz.tu-graz.ac.at (Christoph Robitschko) Newsgroups: comp.os.386bsd.development Subject: Re: kernel hacking tips Date: 12 May 1993 09:11:48 +0200 Organization: Technical University of Graz, Austria Lines: 30 Message-ID: <1sq7vkINNnai@fstgds01.tu-graz.ac.at> References: <1993May11.192459.1618@ucsu.Colorado.EDU> NNTP-Posting-Host: fstgds01.tu-graz.ac.at X-Newsreader: TIN [version 1.1 PL7] In article <1993May11.192459.1618@ucsu.Colorado.EDU> GALBRAITH JOHN (galbrait@rintintin.Colorado.EDU) wrote: > This is great news. Thanks for the advice. However, you still have to > reboot (and wait for the fsck and the mounts, and ...) every time you actually > try out new changes right? You can get around the fsck by using fastboot, or you can tell the bootblocks to boot the kernel singleuser, and then type ^D to boot up without fsck. I like to test kernel mods in singleuser mode, because the root file system is still mounted read-only, so it is not so easy to destroy everything. > > Has anybody tried to cheat and write a driver that does nothing but give > you access to an outb() and inb() instruction? This might speed development > for a big project. The new driver gets written and debugged before it is ever > added to the kernel so you don't have to constantly reboot. Or what about > doing an inline assembly call to outb with no kernel support at all? You can simply look in the pccons.c file how the X-server gains permission to do I/O instructions (in function pc_xmode_on). You just have to place an ioctl to just give you I/O permission in any driver (I've used the console driver), call the ioctl from your user-level program and you can use inb and outb in this program (You can take the inb and outb routines from locore.s). If you try to use inb/outb from user level without previously gaining permission will abort your program. > > john > galbrait@rintintin.colorado.edu > > Christoph