Date: Tue, 30 Jan 2018 17:04:37 +0000 From: Brooks Davis <brooks@freebsd.org> To: Alan Somers <asomers@freebsd.org> Cc: Andre Albsmeier <Andre.Albsmeier@siemens.com>, Dimitry Andric <dim@freebsd.org>, FreeBSD <freebsd-stable@freebsd.org>, Mike Karels <mike@karels.net> Subject: Re: i386 with 4GB RAM: less than 2GB available on A2SAV (Intel Atom E3940) Message-ID: <20180130170437.GA26561@spindle.one-eyed-alien.net> In-Reply-To: <CAOtMX2jHSD0tSus0gjeHR5UERzgkK1%2BxYNd=Haz-EKVsZGZ8Fw@mail.gmail.com> References: <FF56490E-BD56-4BF1-B1D7-866ACEB32DC4@FreeBSD.org> <201801281632.w0SGWiui055204@mail.karels.net> <20180130071123.GB43715@bali> <CAOtMX2jHSD0tSus0gjeHR5UERzgkK1%2BxYNd=Haz-EKVsZGZ8Fw@mail.gmail.com>
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--azLHFNyN32YCQGCU Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jan 30, 2018 at 07:09:44AM -0700, Alan Somers wrote: > On Tue, Jan 30, 2018 at 12:11 AM, Andre Albsmeier < > Andre.Albsmeier@siemens.com> wrote: >=20 > > On Sun, 28-Jan-2018 at 10:32:44 -0600, Mike Karels wrote: > > > > On 28 Jan 2018, at 15:57, Andre Albsmeier <Andre.Albsmeier@siemens.= com> > > =3D > > > > 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. > > > > >=3D20 > > > > > 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: > > > > >=3D20 > > > > > FreeBSD 11.1-STABLE #0: Mon Jan 15 06:57:10 CET 2018 > > > > > ... > > > > > real memory =3D3D 4294967296 (4096 MB) > > > > > avail memory =3D3D 1939558400 (1849 MB) > > > > > ... > > > > >=3D20 > > > > > So do people have any ideas how I might get a bit closer to at le= ast > > > > > 3 GB? I assume there are no FreeBSD knobs which might help but ho= pe > > > > > dies last... > > > > > > > This is a common problem on i386. Most likely some ranges are rese= rved > > > > 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= =2E.. > > > > > > > -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? >=20 > 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 an= y, > you'll have to find a way for the 64-bit machines to find 64-bit kernel > modules. There are some deficiencies in the management space[0], but it should generally work. Where it doesn't it's a bug and usually not too hard to fix. -- Brooks [0] e.g. https://reviews.freebsd.org/D13459 --azLHFNyN32YCQGCU Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEcBAEBAgAGBQJacKWlAAoJEKzQXbSebgfAGu8H/RpfnHfm28hs9HAaA3gE1AMY q5ZoHZNmn3dwgvIAUaf+eo3jaskXQ3jJyLePj0XI58UIEPWuf7tW+mMGYiNYW3u1 BZDP7vxns6KbwJdkRqIcVR/nT9NYyCY//if05mKwKaY2Plp0fkEIgY2La/Stl9jP toNaB5jJ/1NdX9/gwc29XoSy42Bt5muhMZ45yj/h6GZdkMbb7NfyDURNQBWJO4jw h4/W8aSmfeT3JKw5ZCPw6mPUVhVth9V9qB0B6aFftPw6+K+O/r2h0dFFf4wQoXAY CbaT4TBZ4egPFnPqUHEYXfBWVPrKLgFu0l6o44bTeoUtICn9xPI3RLy6ateKAiU= =wILe -----END PGP SIGNATURE----- --azLHFNyN32YCQGCU--
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