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Re: CDROM/DVDROM drives on SATA IDE = no DMA



On Thu, 2006-05-25 at 09:14 -0300, Marcelo Magno T. Sales wrote:
> Hi,
> 
> I have several desktop machines and notebooks which have CDROM / DVDROM 
> connected to IDE SATA interfaces and they all have DMA disabled. Every time 
> the CDROM/DVDROM drives are accessed, the computers slow down a lot and 
> become almost unusable till it's finished. hdparm shows:
> [marcelo sales sf002698 ~]$ /sbin/hdparm /dev/dvd
> 
> /dev/dvd:
>  IO_support   =  0 (default 16-bit)
>  unmaskirq    =  0 (off)
>  using_dma    =  0 (off)
>  keepsettings =  0 (off)
>  readonly     =  0 (off)
>  readahead    = 256 (on)
>  HDIO_GETGEO failed: Inappropriate ioctl for device
> 
> 
> When I try to enable DMA using hdparm, I get:
> [root sf002698 ~]# hdparm -d1 /dev/dvd
> 
> /dev/dvd:
>  setting using_dma to 1 (on)
>  HDIO_SET_DMA failed: Operation not permitted
>  using_dma    =  0 (off)
> 
> 
> Checking the config file for the stock kernel installed in these machines, I 
> see:
> [marcelo sales sf002698 ~]$ grep _BLK_ /boot/config-$(uname -r) | grep SATA
> # CONFIG_BLK_DEV_IDE_SATA is not set
> 
> I assume this is the reason why I can't turn on DMA, am I right? I believe 
> many, many people shall suffer from this problem too. Should I open an RFE 
> asking to enable this in the next kernel or is there a specific reason for 
> not enabling this in the stock kernels? I hope I'll not need to recompile the 
> kernel and install it in all these machines just because of this :)


Please do.

To get good performance I have to add the following to the boot kernel
parameters:

 combined_mode=libata atapi_enabled=1

But the DMA is still not activated, however I can watch DVDs & burn
cd/dvds ok.
-- 
Brian Millett - [ G'Kar, "The War Prayer"]
"So much for Babylon 5's highly vaunted justice."



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