Date: Wed, 5 May 1999 10:01:55 +0100 (BST) From: Doug Rabson <dfr@nlsystems.com> To: CyberPsychotic <fygrave@tigerteam.net> Cc: freebsd-hackers@freebsd.org, tech@openbsd.org Subject: Re: io ports reading/writing Message-ID: <Pine.BSF.4.05.9905051001000.411-100000@herring.nlsystems.com> In-Reply-To: <Pine.GSO.4.05.9905051339310.632-100000@kyrnet.kg>
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On Wed, 5 May 1999, CyberPsychotic wrote: > ~ > ~ I think you just open /dev/io and use inb/outb. Be warned that this will > ~ only work on i386 - the alpha uses a library, libio, to emulate inb/outb > ~ in user programs. > > you say that on i386, > open("/dev/io",O_RDWR); foo=inb(PORT_X); bar=outb(foo,PORT_Y); would work? > if so, in this scheme I don't quite understand how kernel would handle the > access to io ports. F.e. assuming that opening /dev/io, would give > permittions to all io ports would be quite dangerous (since not all programs > which could be permitted to modify cmos, should be permitted to ports > controlling disk access etc). > > would you mind eleborating this abit? > The access control for io ports is controlled by the file-system permissions on /dev/io. In a standard setup, only root can access this device. -- Doug Rabson Mail: dfr@nlsystems.com Nonlinear Systems Ltd. Phone: +44 181 442 9037 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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