cfreelist info

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3 total messages Started by John F Haugh II Wed, 13 Feb 1991 16:45

#358

Author: John F Haugh II
Date: Wed, 13 Feb 1991 16:45

24 lines
1207 bytes

in various system v's the cblock freelist is declared
something like

struct chead cfreelist;

and (struct chead) is 

struct chead {
	struct	cblock	*c_next;
	int	c_size;
	int	c_flag;
}

what the hell is cfreelist.c_size =supposed= to contain?  it
sure doesn't contain the total number of characters available
on the cblock freelist right now.  my x.29 tty driver thanks
you ...

ps - no fair peeking at the source code.
-- 
John F. Haugh II                             UUCP: ...!cs.utexas.edu!rpp386!jfh
Ma Bell: (512) 832-8832                           Domain: jfh@rpp386.cactus.org
"I've never written a device driver, but I have written a device driver manual"
                -- Robert Hartman, IDE Corp.

Re: cfreelist info

#360

Author: Boyd Roberts
Date: Thu, 14 Feb 1991 23:42

18 lines
934 bytes

In article <19050@rpp386.cactus.org> jfh@rpp386.cactus.org (John F Haugh II) writes:
>
>struct chead {
>	struct	cblock	*c_next;
>	int	c_size;
>	int	c_flag;
>}
>

`c_size' contains the size of the cblock data in bytes (ie CLSIZE).

The only reason I could think of them doing this is to enable dynamic
sizing of the cblocks.

Boyd Roberts			boyd@necisa.ho.necisa.oz.au

``When the going gets wierd, the weird turn pro...''

Re: cfreelist info

#361

Author: John F Haugh II
Date: Tue, 19 Feb 1991 14:28

24 lines
1722 bytes

In article <2022@necisa.ho.necisa.oz.au> boyd@necisa.ho.necisa.oz.au (Boyd Roberts) writes:
>`c_size' contains the size of the cblock data in bytes (ie CLSIZE).

I knew that much - I wanted to know "why".

>The only reason I could think of them doing this is to enable dynamic
>sizing of the cblocks.

This seems to be one of the commonly given reason.  I've not read the
more recent AT&T device driver writer's guides to know what they have
to say.  The XENIX device driver supplement gives 'c_size' as the
buffer size, but isn't specific about cfreelist.c_size, which is
actually a different structure type anyhow ...

Thanks for all of your responses.  My X29 tty driver is doing much
better now, thank you ;-)

And the "crash" command that I posted 3 years ago will be reposted
Real Soon Now with enhancements for figuring some of this stuff out.
-- 
John F. Haugh II                             UUCP: ...!cs.utexas.edu!rpp386!jfh
Ma Bell: (512) 832-8832                           Domain: jfh@rpp386.cactus.org
"I've never written a device driver, but I have written a device driver manual"
                -- Robert Hartman, IDE Corp.

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