freebsd stable - Jan 2018 - i386 with 4GB RAM: less than 2GB available on A2SAV (Intel Atom E3940)

On Sun, 28-Jan-2018 at 10:32:44 -0600, Mike Karels
wrote:
> > On 28 Jan 2018, at 15:57, Andre Albsmeier <Andre.Albsmeier at
siemens.com> > > wrote:
> > > I have a lot of machines running with 4 GB physical RAM and, for
> > > some reasons, I still have to use a 32 bits OS.
> > >=20
> > > All of them show something between 3 and 3.5 GB of RAM available
> > > in dmesg but the brand new Supermicro A2SAV really shocked me:
> > >=20
> > > FreeBSD 11.1-STABLE #0: Mon Jan 15 06:57:10 CET 2018
> > > ...
> > > real memory  =3D 4294967296 (4096 MB)
> > > avail memory =3D 1939558400 (1849 MB)
> > > ...
> > >=20
> > > So do people have any ideas how I might get a bit closer to at
least
> > > 3 GB? I assume there are no FreeBSD knobs which might help but
hope
> > > dies last...
> 
> > This is a common problem on i386.  Most likely some ranges are
reserved
> > for I/O mappings, such as video cards.  If you boot with -v, I think
the
> > kernel prints an overview of the physical ram chunks available?  I
don't
> > know of any other way to get such an overview.
> 
> > Another option is to try PAE, but I have no idea how stable that is...
> 
> > -Dimitry
> 
> I suspect that the unavailable RAM has been mapped above 4 GB by the BIOS.
> 
> About PAE: at $JOB, we have a FreeBSD 8.2 system that has been running
> PAE reliably since 8.2 was new.  Also, we ship amd64 systems that run
> mostly 32-bit binaries, which works well.
But can the entire userland be 32 bit only?

Maybe I'll try the PAE thing...

	-Andre

On Tue, Jan 30, 2018 at 12:11 AM, Andre Albsmeier <
Andre.Albsmeier at siemens.com> wrote:
> On Sun, 28-Jan-2018 at 10:32:44 -0600, Mike Karels wrote:
> > > On 28 Jan 2018, at 15:57, Andre Albsmeier <Andre.Albsmeier at
siemens.com>
> > > > wrote:
> > > > I have a lot of machines running with 4 GB physical RAM and,
for
> > > > some reasons, I still have to use a 32 bits OS.
> > > >=20
> > > > All of them show something between 3 and 3.5 GB of RAM
available
> > > > in dmesg but the brand new Supermicro A2SAV really shocked
me:
> > > >=20
> > > > FreeBSD 11.1-STABLE #0: Mon Jan 15 06:57:10 CET 2018
> > > > ...
> > > > real memory  =3D 4294967296 (4096 MB)
> > > > avail memory =3D 1939558400 (1849 MB)
> > > > ...
> > > >=20
> > > > So do people have any ideas how I might get a bit closer to
at least
> > > > 3 GB? I assume there are no FreeBSD knobs which might help
but hope
> > > > dies last...
> >
> > > This is a common problem on i386.  Most likely some ranges are
reserved
> > > for I/O mappings, such as video cards.  If you boot with -v, I
think
> the
> > > kernel prints an overview of the physical ram chunks available? 
I
> don't
> > > know of any other way to get such an overview.
> >
> > > Another option is to try PAE, but I have no idea how stable that
is...
> >
> > > -Dimitry
> >
> > I suspect that the unavailable RAM has been mapped above 4 GB by the
> BIOS.
> >
> > About PAE: at $JOB, we have a FreeBSD 8.2 system that has been running
> > PAE reliably since 8.2 was new.  Also, we ship amd64 systems that run
> > mostly 32-bit binaries, which works well.
>
> But can the entire userland be 32 bit only?
>
Sure.  I do this with jails.  It's no problem to have a 32-bit jail on a
64-bit kernel.  Kernel modules would be an issue, though.  If you need any,
you'll have to find a way for the 64-bit machines to find 64-bit kernel
modules.

>
> Maybe I'll try the PAE thing...
>