Re: Problem with ata layer in 2.6.24

[Mark Lord]

rgheck wrote:
> Mark Lord wrote:
> > rgheck wrote:
> > > Alan Cox wrote:
> > > > > not one problem but lots---is sufficiently widespread that a Mini 
> > > > > HOWTO, say, would be really welcome and, I'm guessing, widely used.
> > > > >     
> > > >
> > > > We don't see very many libata problems at the distro level and they for
> > > > the most part boil down to
> > > >
> > > > - sata_nv with >4GB of RAM, knowing being worked on, no old IDE driver
> > > > anyway
> > > >   
> > > Is this >4GB or >=4GB? I've seen contradictory reports, and I've got 
> > > 4GB.
> > ..
> >
> > For all practical purposes, most memory over 3GB (or sometimes even 2GB)
> > on a 32-bit x86 system is treated as >4GB by the motherboard.
> >
> > Because it's not the amount of *memory* that matters so much,
> > but rather the amount of *used address space*.  Video cards,
> > PCI devices, other motherboard resources etc.. can all subtract
> > from the available address space, leaving much less than 4GB
> > for your RAM.
>
> Right. So it looks like I do have this issue, though I haven't seen any 
> actual problems on 24. Is there a known workaround?
..

For now, the workaround is to not enable the RAM above 4GB.
Your kernel .config file should therefore have these two lines:

CONFIG_HIGHMEM4G=y
# CONFIG_HIGHMEM64G is not set

Later, once the issue is fixed at the driver level (soon),
you can get your high memory back again by enabling CONFIG_HIGHMEM64G,
though this will cost a few percent of performance in the extra
page table overhead it creates.

Cheers
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