Memory 64bit see 8gigs but can only use 4gigs
davej at redhat.com
Fri Sep 30 22:55:27 UTC 2005
On Fri, Sep 30, 2005 at 06:48:16PM -0400, Chris Miller wrote:
> On Fri, 2005-09-30 at 18:23, Dave Jones wrote:
> > On Fri, Sep 30, 2005 at 06:06:59PM -0400, Chris Miller wrote:
> > > kernel: Memory: 3992156k/8388608k available (2242k kernel code, 0k
> > > reserved, 1322k data, 224k init)
> > >
> > > total used free shared buffers
> > > cached
> > > Mem: 3993352 2541436 1451916 0 526208
> > > 481032
> > > -/+ buffers/cache: 1534196 2459156
> > > Swap: 0 0 0
> > >
> > > 2.6.13-1.1526_FC4smp #1 SMP Wed Sep 28 19:28:24 EDT 2005 x86_64 x86_64
> > > x86_64 GNU/Linux
> > >
> > > Any idea why I can see all 8gigs but can only use 4gigs?
> > Try booting with numa=noacpi
> > If this works, it's a buggy bios.
> That is the fix thank you.
> Was starting to think it was me =)
There are two means of finding the total amount of ram.
The old legacy 'e820' tables, and the newer 'srat' tables.
A while ago, we started using srat on x86-64, as it allows
us to determine how much memory is local to each cpu, rather
than the 'global' view that e820 gives us.
In an ideal world, the two should be in sync.
Some vendors however seem to create tables that don't tally,
so ram disappears when you use the srat approach.
Is this a Tyan board by any chance ?
They seemed to be quite badly affected by this issue, and
did put out bios updates for some, but not all boards.
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