[Techtalk] MTRR info please

[Gebhard Dettmar]

On Sunday 16 October 2005 02:22, Patricia Fraser wrote:
> Hello all,
>
> recently (since using kernels 2.6.10 and above) I've been getting a "no
> more MTRRs available" message at boot time, so I did a bit of googling

So with Kernel < 2.6.10 you didn't get the messages?

> and I'm not really a lot the wiser. My /proc/mtrr looks like this:
>
> [...]
>
> I've looked at the BIOS, and there doesn't seem to be much I can do to
> tweak what memory is set aside for graphics. Will it maybe make a
> difference if I set X up to use less video ram? I'm hoping for
> something that will use a bit less of my poor CPU, which seems to be on
> 99% more of the time than I'm happy with.
>
> Any clues where I could go for more reading?
>
Unfortunately not. I get the same messages on my laptop and didn't get any 
wiser than you with Google. On my debian-user-german-list someone wrote 
the clearest answer I found, so I'll try to translate it here
--
MTRRs (Memory Type Range Register) are CPU-Registers that the HW uses to 
controll settings of certain memory-ranges, e.g. that the memory of your 
graphic underlies certain rules. Those settings are typically controlled 
by device-drivers. The amount of registers is limited, so if too many 
devices are registered you get the the above message: no more MTRRs. This 
is nothing to worry about, you'll lose some performance (a few percent) 
when accessing those devices that didn't get their share of mtrr
--
To me that sounded like: can't do anything but nothing to worry about 
anyway
> Cheers,
dito
geb