Path: utzoo!utgpu!watserv1!watmath!uunet!snorkelwacker!mit-eddie!andante!ulysses!dptg!mtune!jcm
From: jcm@mtune.ATT.COM (John McMillan)
Newsgroups: unix-pc.general
Subject: Re: HELP with *BLOCK* device driver
Message-ID: <300@mtune.ATT.COM>
Date: 6 Feb 90 17:23:36 GMT
References: <1990Feb5.074541.26335@stb.uucp> <1087@icus.islp.ny.us>
Distribution: unix-pc
Organization: AT&T BL Middletown/Lincroft NJ USA
Lines: 27

In article <1087@icus.islp.ny.us> lenny@icus.islp.ny.us (Lenny Tropiano) writes:
:
>Ahh, I remember this well! :-)  For some reason or another, a entry point
>in the device driver called "drvprint()" is required. 
>drv is the driver name (ie. nfs) and the masterupd line being:
>
># masterupd -a block open close strategy release print nfs
>
>The print-entry-point isn't discussed, at least to my recollection, in
>the "Writing a Device Driver Guide" so I don't even know what it does,
>and why it _might_ be called.
:
	1) It is ridiculous that an unsupplied PRINT param is not
		converted to a null procedure call.  Not my code.
		"They" were probably rushed -- EVERYONE was rushed.

	2) 'prdev()' is used to print FS errors: eg.,
			prdev("Bad free count", dev);
		'prdev(str,dev)' calls
			(*bdevsw[bmajor(dev)].d_print)(minor(dev), str);
		This permits logging or other activities particular
		to that device.

	3) All -- the ONLY 8-) -- built-in BLOCK drivers ignore the
		feature by using 'nulldev' as the value for the procedure.

jcm -- muttering for self, not them