From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from wr-out-0506.google.com (wr-out-0506.google.com [64.233.184.237]) by ozlabs.org (Postfix) with ESMTP id 9067B679E9 for ; Fri, 20 Oct 2006 02:23:27 +1000 (EST) Received: by wr-out-0506.google.com with SMTP id 50so177116wri for ; Thu, 19 Oct 2006 09:23:26 -0700 (PDT) Message-ID: Date: Thu, 19 Oct 2006 21:53:24 +0530 From: "Rahul Theraja" To: "Shakthi Kannan" Subject: Re: help in block drivers In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_156228_15324467.1161275004769" References: Cc: kernelnewbies@nl.linux.org, linuxppc-embedded@ozlabs.org List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , ------=_Part_156228_15324467.1161275004769 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline Hello Shakthi Kannan, Thanks for the reply . > driver. I could not understand why the "sbd_request " is called even > though > > i have given only one read call from user space file. > > Block device I/O transfer is done in blocks. > > > And also in the driver, in the function sbd_request() how does the > driver > > get the parameters like sector, current_nr_sectors and buffer. > > VFS <-> SCSI <-> Block device? > > > i could move > > furhter fastly. > > Fastly? IMHO, learning kernel development involves lot of patience. > > SK Is it necessary to use kernel_thread() in block drivers. In drivers/block loop.c i could see kernel_thread() being used but in floopy.c it is not used. When is this kernel_thread() function is supposed to be used ? In the sbd_device also the kernel_thread() is not used. Anyone please kindly clarify my doubts. Thanks in Advance -Rahul ------=_Part_156228_15324467.1161275004769 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline Hello Shakthi Kannan,

Thanks for the reply .

> driver. I could not understand why the "sbd_request " is called even though
> i have given only one read call from user space file.

Block device I/O transfer is done in blocks.

>  And also in the driver, in the function sbd_request() how does the driver
> get the parameters  like sector, current_nr_sectors and buffer.

VFS <-> SCSI <-> Block device?

> i could move
> furhter fastly.

Fastly? IMHO, learning kernel development involves lot of patience.

SK


Is it necessary to use kernel_thread() in block drivers. In  drivers/block loop.c i could see  kernel_thread() being used but in floopy.c it is not used. When is this kernel_thread() function is supposed to be used ?  In the sbd_device also the kernel_thread() is not used.

Anyone please kindly clarify my doubts.

Thanks in Advance

-Rahul
 

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