quoted text > Yinghai Lu schrieb:
>
>
> > On Thu, May 1, 2008 at 5:09 AM, Mika Fischer <mika.fischer@zoopnet.de> wrote:
> >> Yinghai Lu schrieb:
> >>
> >>> loop mtrr chunk_size and gran_size from 1M to 2G to find out optimal value.
> >> >
> >> > so user don't need to add mtrr_chunk_size and mtrr_gran_size,
> >> >
> >> > if optimal value is not found, print out all list to help select less optimal
> >> > value.
> >> >
> >> > add mtrr_spare_reg_nr= so user could set 2 instead of 1, if the card need more entries.
> >>
> >> On my system x86-latest + this patch and using no boot options gives me
> >> this /proc/mtrr:
> >> reg00: base=0x00000000 ( 0MB), size=2048MB: write-back, count=1
> >> reg01: base=0x80000000 (2048MB), size= 512MB: write-back, count=1
> >> reg02: base=0xa0000000 (2560MB), size= 256MB: write-back, count=1
> >> reg03: base=0xb0000000 (2816MB), size= 256MB: write-back, count=1
> >> reg04: base=0xbf700000 (3063MB), size= 1MB: uncachable, count=1
> >> reg05: base=0xbf800000 (3064MB), size= 8MB: uncachable, count=1
> >> reg06: base=0x100000000 (4096MB), size=1024MB: write-back, count=1
> >>
> >> Which is OK. It could probably collapse reg01-reg03 into one but that's
> >> a minor issue (for me at least, there are probably cases where
> >> collapsing them might save the user from having to specify the
> >> mtrr_spare_reg_nr boot option).
> >
> > yes. please try mtrr_spare_reg_nr=3 or etc.
>
> Sure this works. But that was my point exactly. It should be possible to
> figure out the better configuration automatically so that I *don't* have
> to specify mtrr_spare_reg_nr=3.
>
> Or in other words: If there are multiple equivalent configurations that
> don't lose any RAM(!), the one with the most free MTRR regs should be
> preferred.
>
> AFAICT you loop over the chunk size and stop when you have found a
> configuration that leaves the number of free MTRR registers requested
> (default 1).
>
> This will almost always result in a configuration where you have
> *exactly* the number of requested free regs available, even if a more
> efficient configuration was possible.
