Re: new tool: blktool

[Jeff Garzik]

Mark Lord wrote:
> Supplementary or Alternatively, all of the ATA device commands issued by 
> hdparm
> can be supported in a driver by simply implementing the HDIO_DRIVE_CMD
> ioctl -- This is only a few lines of code in a typical SATA/SCSI driver,
> and I could easily supply a patch to implement it in libata.
>
> Sure it's old, looks clunky, but it is simple code that works
> and is used by many more tools than just hdparm today.


True but I'm wrestling with one of its design flaws...  it doesn't 
provide the taskfile protocol.

I really really want to know before the command is submitted whether I 
am going to be receiving data, sending data, or neither.  The current 
IDE driver "guesses" by virtue of DRQ flag behavior, but such a guess is 
impossible on modern SATA controllers.

You either have to provide a lookup table (command opcode -> protocol), 
or specify it through the userland API.  HDIO_DRIVE_TASKFILE does this 
via 'data_phase'.

On a more general note, though, I certainly welcome libata patches from 
any and all sources.  Hack away!

	Jeff


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