Re: Problem with ata layer in 2.6.24

From: Mark Lord
Date: Tue Jan 29 2008 - 13:32:28 EST


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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