On Friday 22 June 2007, Mark Lord wrote: > Alan Cox wrote: > > On Fri, 22 Jun 2007 11:01:09 -0400 > > Mark Lord <liml@xxxxxx> wrote: > > > >> Alan Cox wrote: > >>> Allow > >>> > >>> libata.pata_dma=0 > >>> > >>> to disable DMA (default is 1) > >>> > >>> SATA is unaffected as disabling DMA for SATA makes no sense at all. > >>> > >>> Signed-off-by: Alan Cox <alan@xxxxxxxxxx> > >> Alan, > >> > >> Should we really be piling up like this on global boot/module options > >> rather than run-time flags on individual channels/devices ? > >> > >> I can imagine systems with internal notebook drives that want dma=1, > >> plus Cardbus CF devices that require dma=0. > >> > >> With a single global flag, how does one do that? > > > > We need proper tuning as well but there is huge value (with distro hat > > on especially) in a single "try this to get it installed and then we can > > debug it" button. Same with the old IDE. Trying to guide users through > > selecting specific channels/devices is going to be painful. I want > > something that I can tell people to get them 'off the ground' and work > > with them to sort the rest. > > Oh for sure. I'm just thinking that some form of on-the-fly tunable > would be of even greater value here, in addition to the boot/load default flag. > > I think a /sys/ "dma" attribute (pick a name) might be most appropriate, > or we just just implement HDIO_[GS]ET_DMA as a simpler/lazier mechanism. The problem is that libata lacks any locking needed for having this (and other useful) settings tunable on per device basis. IDE has a needed locking although it sucks a lot (but is being reworked). Bart - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
