Subject: RE: G4 maximum memory?
To: 'David Bryan' <videoman@visi.com>
From: Cliff Neighbors <cliff@allegronetworks.com>
List: port-macppc
Date: 08/04/2000 16:03:17
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here's a real world data point:
today I loaded up a G4 with 2GB (4x 512MB DIMMs)
but it wasn't much fun:
panic: poalloc
early on in main() i.e.
main-->uvm_init-->uvm_page_init-->uvm_pageboot_alloc-->
pmap-->kenter_pa-->pmap_enter-->pmap_copy_page-->poalloc
this is from the section of pmap_enter()\pmap.c
where pte_insert() returns 0 which apparently means
need to allocate an "overflow entry".
the comment at the head of poalloc() is interesting:
/*
* We really hope that we don't need overflow entries
* before the VM system is initialized!
XXX
*/
in the failing instance, pmap_enter was called with
va = 0xe0801000, pa = 0xb6a000
in case that rings bells for anyone?
regards,
-cliff-
---
cliff neighbors
allegro networks, inc.
cliff@allegronetworks.com
408-821-5532
---
-----Original Message-----
From: David Bryan [mailto:videoman@visi.com]
Sent: Friday, August 04, 2000 2:30 PM
To: Cliff Neighbors
Cc: 'port-macppc@netbsd.org'
Subject: Re: G4 maximum memory?
On Tue, Aug 01, 2000 at 12:53:50PM -0700, Cliff Neighbors had written:
> the G4 sawtooth motherboard has 4 DIMM slots which can each
> take up to 512MB. MacOS can only address 1.5GB, which I have heard
> is a software limit.
>
> has anyone tried running netbsd-macppc on a 2GB configuration?
> is there a known limit < 2GB on physical memory size either in the G4
> hardware
> (e.g. DMA limit?) or the macppc kernel?
>
From what I've heard it's just MacOS, but MacOSX will address more memory.
So, that being said, I would assume that Other OSes can address more memory.
--
//\\
VideoMan //()\\ aka DaVinci (David M.N. Bryan)
//__|_\\
//__|__|\\ No connection to CPU.
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<P><FONT SIZE=3D2>here's a real world data point:</FONT>
<BR><FONT SIZE=3D2>today I loaded up a G4 with 2GB (4x 512MB =
DIMMs)</FONT>
<BR><FONT SIZE=3D2>but it wasn't much fun:</FONT>
</P>
<P> <FONT SIZE=3D2>panic: =
poalloc</FONT>
</P>
<P><FONT SIZE=3D2>early on in main() i.e.</FONT>
</P>
<P> <FONT =
SIZE=3D2>main-->uvm_init-->uvm_page_init-->uvm_pageboot_alloc--=
></FONT>
<BR> =
<FONT =
SIZE=3D2>pmap-->kenter_pa-->pmap_enter-->pmap_copy_page-->po=
alloc</FONT>
</P>
<P><FONT SIZE=3D2>this is from the section of =
pmap_enter()\pmap.c</FONT>
<BR><FONT SIZE=3D2>where pte_insert() returns 0 which apparently =
means</FONT>
<BR><FONT SIZE=3D2>need to allocate an "overflow =
entry".</FONT>
</P>
<P><FONT SIZE=3D2>the comment at the head of poalloc() is =
interesting:</FONT>
</P>
<P><FONT SIZE=3D2>/*</FONT>
<BR><FONT SIZE=3D2> * We really hope that we don't need overflow =
entries</FONT>
<BR><FONT SIZE=3D2> * before the VM system is initialized!</FONT>
<BR><FONT SIZE=3D2> =
XXX</FONT>
<BR><FONT SIZE=3D2> */</FONT>
</P>
<P><FONT SIZE=3D2>in the failing instance, pmap_enter was called =
with</FONT>
<BR><FONT SIZE=3D2>va =3D 0xe0801000, pa =3D 0xb6a000</FONT>
<BR><FONT SIZE=3D2>in case that rings bells for anyone?</FONT>
</P>
<P><FONT SIZE=3D2>regards,</FONT>
<BR> <FONT =
SIZE=3D2>-cliff-</FONT>
</P>
<P><FONT SIZE=3D2>---</FONT>
<BR><FONT SIZE=3D2>cliff neighbors</FONT>
<BR><FONT SIZE=3D2>allegro networks, inc.</FONT>
<BR><FONT SIZE=3D2>cliff@allegronetworks.com</FONT>
<BR><FONT SIZE=3D2>408-821-5532</FONT>
<BR><FONT SIZE=3D2>---</FONT>
</P>
<BR>
<P><FONT SIZE=3D2>-----Original Message-----</FONT>
<BR><FONT SIZE=3D2>From: David Bryan [<A =
HREF=3D"mailto:videoman@visi.com">mailto:videoman@visi.com</A>]</FONT>
<BR><FONT SIZE=3D2>Sent: Friday, August 04, 2000 2:30 PM</FONT>
<BR><FONT SIZE=3D2>To: Cliff Neighbors</FONT>
<BR><FONT SIZE=3D2>Cc: 'port-macppc@netbsd.org'</FONT>
<BR><FONT SIZE=3D2>Subject: Re: G4 maximum memory?</FONT>
</P>
<BR>
<P><FONT SIZE=3D2>On Tue, Aug 01, 2000 at 12:53:50PM -0700, Cliff =
Neighbors had written:</FONT>
<BR><FONT SIZE=3D2>> the G4 sawtooth motherboard has 4 DIMM slots =
which can each</FONT>
<BR><FONT SIZE=3D2>> take up to 512MB. MacOS can only address =
1.5GB, which I have heard</FONT>
<BR><FONT SIZE=3D2>> is a software limit. </FONT>
<BR><FONT SIZE=3D2>> </FONT>
<BR><FONT SIZE=3D2>> has anyone tried running netbsd-macppc on a 2GB =
configuration? </FONT>
<BR><FONT SIZE=3D2>> is there a known limit < 2GB on physical =
memory size either in the G4</FONT>
<BR><FONT SIZE=3D2>> hardware </FONT>
<BR><FONT SIZE=3D2>> (e.g. DMA limit?) or the macppc kernel? </FONT>
<BR><FONT SIZE=3D2>> </FONT>
</P>
<P><FONT SIZE=3D2>From what I've heard it's just MacOS, but MacOSX will =
address more memory.</FONT>
<BR><FONT SIZE=3D2>So, that being said, I would assume that Other OSes =
can address more memory.</FONT>
</P>
<P><FONT SIZE=3D2>-- </FONT>
<BR><FONT =
SIZE=3D2> =
//\\</FONT>
<BR><FONT SIZE=3D2>VideoMan //()\\ aka DaVinci (David M.N. =
Bryan)</FONT>
<BR><FONT SIZE=3D2> =
//__|_\\ </FONT>
<BR><FONT SIZE=3D2> =
//__|__|\\ No connection to CPU.</FONT>
</P>
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