Re: set blksize of block device

[Lei Yang <lya755@ece.northwestern.edu>]

Shesha B. Sreenivasamurthy wrote:

>Firstly you cannot set the block size to lesser than 512. 
>
>When there is a request for the IO, you populate "struct req" data
>structure which you will pass it to the kernel or lower level SCSI/SATA
>driver. In the "struct req" there is a field "b_size" which may be what
>you are interested in. At the user level you can use the IOCTLs to set
>the block size of the RAW block device.
>
>-Shesha
>  
>
I understand that for real block device (like hard disk), block size 
cannot be less than 512. But to ramdisks, I think they are truely random 
addressable, and should be able to move on blocks even with size of 2 bytes.

Any comments?

>On Wed, 2004-10-27 at 18:44, Lei Yang wrote:
>  
>
>>If nobody could answer this question, what about another one? Is there a 
>>system call or a kernel interface that would allow me to write a block 
>>of data to block 1 of a certain block device?
>>
>>Thanks for your reply in advance!
>>
>>Lei
>>
>>Lei Yang wrote:
>>
>>    
>>
>>>Please cc me if you have answers to this, I am not on the list. Thanks 
>>>a lot!
>>>
>>>Lei Yang wrote:
>>>
>>>      
>>>
>>>>Hello,
>>>>
>>>>I am learning block device drivers and have a newbie question. Given 
>>>>a block device, is there anyway that I could set its block size? For 
>>>>example, I want to write a block device driver that will work on an 
>>>>existing block device.  In this driver, I want block size smaller. 
>>>>(The idea looks confusing but I could explain if anybody is 
>>>>interested :- )  However,  typically the block size is 1KB, now I 
>>>>want to set it to 512 or 256.  Can I do it?
>>>>
>>>>TIA
>>>>Lei
>>>>
>>>>        
>>>>
>>>
>>>      
>>>
>>
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