Re: AHCI and add_disk_randomness()

[Jens Axboe <jens.axboe@oracle.com>]

On Wed, Nov 15 2006, Marek Podmaka wrote:
> Hello,
> 
>   I have server with Intel 5000V motherboard with integrated AHCI SATA
>   controller. It works well with kernel 2.6.18.2. But I have problem
>   with little entropy available and I'm not sure if one of the reasons
>   is that AHCI driver does not use add_disk_randomness() to contribute
>   to the kernel entropy pool.
> 
>   I'm not very skilled on kernel "hacking"... I tried finding where
>   this is called (it's defined in drivers/char/random.c and used for
>   example in Comapaq SmartArray driver in drivers/block/cciss.c). For
>   the SCSI part, I found it in scsi_lib.c, but I was not able to
>   determine if this is actually used by ahci/libata drivers.
> 
>   If not, would it be possible to implement it? I tried to figure out
>   where to call it by looking at cciss.c, but it seems that this is
>   totally different case, at least for me. I don't know where to add
>   it, because its parameter is struct gendisk *disk and didn't find it
>   used anywhere in ahci or libata.

Since ahci attaches its devices through the scsi layer,
add_disk_randomness() will get called from scsi_end_request() like for
any other scsi controller.

-- 
Jens Axboe