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Re: ahcisata usage mode (on NetBSD 6.1.1 (GENERIC) amd64)

On 28-09-13 13:36, Manuel Bouyer wrote:
On Sat, Sep 28, 2013 at 10:35:16AM +0200, Job Hanssen wrote:
wd4 at atabus4 drive 0
wd4: <WDC WD10EAVS-00D7B0>
wd4: drive supports 16-sector PIO transfers, LBA48 addressing
wd4: 931 GB, 1938021 cyl, 16 head, 63 sec, 512 bytes/sect x 1953525168
wd4: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 6 (Ultra/133)
wd4(ahcisata0:4:0): using PIO mode 4, DMA mode 2, Ultra-DMA mode 6
(Ultra/133) (using DMA)

>From the "(using DMA)" in the last line for each drive, I undertand that
I'm currenctly running DMA mode 2. Am I correct?
No, it's really using the hightest (U)DMA mode available. The "using DMA"
is just there to mention that when possible it won't use PIO to transfer
ATA has 2 way to transfer data: PIO and DMA, with different commands.
Ultra-DMA is just a sub-class of DMA and the same commands will do
either DMA or Ultra-DMA, depending on what's available.

Thanks for clarifying. I obviously misinterpreted that.

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