Date: Tue, 1 Jun 1999 12:29:26 -0700 (PDT) From: Julian Elischer <julian@whistle.com> To: Wes Peters <wes@softweyr.com> Cc: Zhihui Zhang <zzhang@cs.binghamton.edu>, freebsd-hackers@FreeBSD.ORG Subject: Re: Accessing special device files Message-ID: <Pine.BSF.3.95.990601122733.13159A-100000@current1.whistle.com> In-Reply-To: <37542B43.FD1CFFF3@softweyr.com>
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On Tue, 1 Jun 1999, Wes Peters wrote: > > dd verifies the behavior you report: > > root@homer# dd if=/dev/rwd0s2b of=/dev/null bs=1 > dd: /dev/rwd0s2b: Invalid argument > ... > root@homer# dd if=/dev/rwd0s2b of=/dev/null bs=512 > ^C18805+0 records in > ... > > wes@homer$ ls -l /dev/*wd0s2a > crw-r----- 1 root operator 3, 0x00030000 Apr 1 11:10 /dev/rwd0s2a > brw-r----- 1 root operator 0, 0x00030000 Apr 1 11:10 /dev/wd0s2a > > The rwd device is clearly a character-special device, the wd device a > block special. Character devices can always be read byte-at-a-time, > by definition. When did the semantics of this change? It's always been this way think of the devices as "RAW and buffered", rather than "character and block" RAW devices are limted by the hardware limtiations. Buffered devices use buffering to hide those limitations. > > -- > "Where am I, and what am I doing in this handbasket?" > > Wes Peters Softweyr LLC > http://www.softweyr.com/~softweyr wes@softweyr.com > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hackers" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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