----- Original Message ----- > From: Mark Kettenis <mark.kette...@xs4all.nl> > Sent: Tuesday, September 20, 2011 4:57 AM > Subject: Re: Disabling PIO / LBA48 on large drives , Blade 150
> In wd(4), we only actually use the LBA48 flag for requests that > actually need it (see __wdstart()). So reads and writes from/to the > start of the disk will use the LBA flag and use DMA just fine. > > So just make sure you keep the end of your disks empty and things > should just work fine. Thank you for pointing this out. After seeing Nick Holland's message, I looked at your commit for rev 1.322 of pciide.c and then wondered what I was missing since I had already been looking at the 4.9 sources. A closer inspection of the code revealed exactly what you said here. Thanks for the changes in the driver and also for your message here. May I suggest a note in the pciide(4) manpage mentioning that PIO is only used by default on the M5229 for transfers above 128 GiB? It could go in the "BUGS" section where the quirks of other controllers are also discussed. I would be happy to write such a note up and provide a diff if you'd like. Best regards.
