Subject: Re: My mails never show up ...
To: Stefan Sonnenberg-Carstens <email@example.com>
From: Bill Studenmund <firstname.lastname@example.org>
Date: 03/21/2003 10:20:40
On Fri, 21 Mar 2003, Stefan Sonnenberg-Carstens wrote:
> ... sad but true.
> I've send my question four times now, under 2 different emails :
> email@example.com and firstname.lastname@example.org.
> Also, the number of emails I receive from tech-kern does not match
> the value showing if i take a look at the recent archive for today.
Hmmm. Well, this one made it.
> Please, help.
> Here my original posting :
> Hi List,
> I'm new to NetBSD kernel development and right now, I'm trying to get the
> big picture of how the NetBSD kernel works. (I did device driver programing
> on Linux befor).
> I followed some docs and found that a device driver (can/should) support
> these operations:
> open,close,probe,attach,read,write,ioctl - complete ?
> What about the seek operation ?
> I didn't find it.
> Is this something that has to do with the uio->uio_offset stuff ?
> This was the only thing, that made sense to me.
Yes. "seeking" is a concept that goes with a file descripter, since it has
the offset pointer that a seek moves.
By the time operations get down to the device drivers, they are for
specific parts of the disk. The driver doesn't know if we're reading a
given block because there was a seek that got us there, or becuase we've
read everything else up to it.
Check out kern/vfs_syscalls.c:sys_lseek()