Date: Mon, 19 Feb 2018 19:44:13 +0100 From: Andre Albsmeier <Andre.Albsmeier@siemens.com> To: Mike Karels <mike@karels.net> Cc: Dimitry Andric <dim@FreeBSD.org>, Andre Albsmeier <Andre.Albsmeier@siemens.com>, freebsd-stable@freebsd.org Subject: Re: i386 with 4GB RAM: less than 2GB available on A2SAV (Intel Atom E3940) Message-ID: <20180219184413.GA9910@bali> In-Reply-To: <201801281632.w0SGWiui055204@mail.karels.net> References: <FF56490E-BD56-4BF1-B1D7-866ACEB32DC4@FreeBSD.org> <201801281632.w0SGWiui055204@mail.karels.net>
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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> = > > 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. Finally I found some time to play with the PAE option. I added option PAE option KVA_PAGES=1024 and the A2SAV booted and gave me real memory = 4294967296 (4096 MB) avail memory = 4048207872 (3860 MB) Very encouraging, this is double of what I had before! So I decided to try this on my desktop machine which also boots but loading the i915kms and drm2 stuff fails with info: [drm] Initialized drm 1.1.0 20060810 drmn0: <Intel IvyBridge> on vgapci0 error: [drm:pid949:i915_gem_gtt_init] *ERROR* Scratch setup failed device_attach: drmn0 attach returned 12 The KMS stuff doesn't support the A2SAV anyway so I can't test how it would behave there...
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