# Not able to enable DMA on my harddisk

## Zu`

When I do

```

hdparm /dev/hda

```

It shows that dma is not enabled.

I tried hdparm -d1 /dev/hda but then it says:

 *Quote:*   

> 
> 
> /dev/hda:
> 
>  setting using_dma to 1 (on)
> ...

 

I've tried different settings in my kernel config, but can't seem to find the right one. And strange thing is, I used my old kernel config (previous install of gentoo) and then DMA was working and now it isn't!

Any help on this please, I really need DMA to be enabled, it makes a huge difference. Also would like to know how to enable it on my cd-writer (scsi-emulated device on /dev/sr0 ) -- or how to check this?

All help is appreciated.

Thanks.

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## lx

You have to compile it in your kernel:

 *Quote:*   

> ATA/IDE...->ATA/IDE....->[*] Generic PCI Bus-master DMA support

 

I also have the following selected

 *Quote:*   

> Use PCI DMA by default when available

 

This way I don't have to use hdparm, but read the help, some bugs or something.

For cdr when I do cat /proc/ide/hdc/settings the using_dma is on, so I think it's using dma (hdparm doesn't work on scsi-emulation).

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## Zu`

That worked btw  :Wink: 

Just didn't seem logic as it said PCI

I thought it was something special

Thanks for your help, kinda lost track of this post  :Wink: 

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## niyogi

I have the same problem but I had those two checked when I compiled the kernel.  but it doesn't seem to work still (meaning I still get the error)

-S

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