IOMMU option in bios
in [Debian]
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From: Charles Kroeger on 17 Mar 2010 20:30 I was looking over a dmesg output and I noticed a message that said I would save 64MB of RAM if I enabled the IOMMU option in the bios. I'm using an ASUS M4A79XTD EVO board with 8GB of RAM so maybe freeing up 64MB of RAM isn't that big of a deal; however, I had a look in the bios setup and saw nothing that pertained to IOMMU to enable. The BIOS is an 8MB Flash ROM, AMI BIOS PnP etc. Can anyone eleborate on this message in dmesg? -- C -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org Archive: http://lists.debian.org/20100317200830.65e8609f(a)Mondo
From: Camaleón on 18 Mar 2010 12:00 On Wed, 17 Mar 2010 20:08:30 -0400, Charles Kroeger wrote: > I was looking over a dmesg output and I noticed a message that said I > would save 64MB of RAM if I enabled the IOMMU option in the bios. > > I'm using an ASUS M4A79XTD EVO board with 8GB of RAM so maybe freeing up > 64MB of RAM isn't that big of a deal; however, I had a look in the bios > setup and saw nothing that pertained to IOMMU to enable. > > The BIOS is an 8MB Flash ROM, AMI BIOS PnP etc. > > Can anyone eleborate on this message in dmesg? Not sure if this has something to do with some BIOS option that allow "memmory remapping" :-? There is an Ubuntu forum thread that may help a bit: *** "Your BIOS doesn't leave a aperture memory hole" / "This costs you 64 MB of RAM" http://ubuntuforums.org/showthread.php?t=1018854&highlight=enable+iommu+option+bios *** Greetings, -- Camaleón -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org Archive: http://lists.debian.org/pan.2010.03.18.15.58.07(a)gmail.com
From: Clive McBarton on 18 Mar 2010 20:10 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Camaleón wrote: > Not sure if this has something to do with some BIOS option that allow > "memmory remapping" :-? There's no such option. Not in any BIOS I've ever seen. > There is an Ubuntu forum thread that may help a bit It doesn't. It's a long thread with people talking about the problem, suggesting a great number of "solutions" (some of them harmful) without solving the problem. On the other hand, nothing else I've seen so far solves the problem either. Most people ignore it, since it may be just an annoying message, the loss of a tiny fraction of RAM, and possibly your RAM becoming slightly slower. Are there any users of 64bit Debian with 4GB or more who are not affected? -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkuivyoACgkQ+VSRxYk440/7WQCgs02+kUgIU1ZVaNdU+fdA5WKF TwwAoIHuqG+ZIB9LybyEqcwsF1yth2jf =WAWp -----END PGP SIGNATURE----- -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org Archive: http://lists.debian.org/4BA2BF2A.1070604(a)web.de
From: Camaleón on 19 Mar 2010 03:40 On Fri, 19 Mar 2010 01:02:50 +0100, Clive McBarton wrote: > Camaleón wrote: >> Not sure if this has something to do with some BIOS option that allow >> "memmory remapping" :-? > > There's no such option. Not in any BIOS I've ever seen. That could be the problem. >> There is an Ubuntu forum thread that may help a bit > > It doesn't. It's a long thread with people talking about the problem, > suggesting a great number of "solutions" (some of them harmful) without > solving the problem. Didn' you try some of the tips? They only require passing some options to the kernel at boot time and there is nothing harmful in doing that :-? > On the other hand, nothing else I've seen so far solves the problem > either. Most people ignore it, since it may be just an annoying message, > the loss of a tiny fraction of RAM, and possibly your RAM becoming > slightly slower. I passed the link not because it provided a "magic solution" but for you get an idea of the origin of that message and how to bypass it ;-) > Are there any users of 64bit Debian with 4GB or more who are not > affected? Sure. I am not getting that message in dmesg (running lenny amd64, 8 GiB.) *but* my BIOS has "memory reclaiming" enabled. Greetings, -- Camaleón -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org Archive: http://lists.debian.org/pan.2010.03.19.07.30.58(a)gmail.com
From: Clive McBarton on 19 Mar 2010 18:50 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Camaleón wrote: > Didn' you try some of the tips? They only require passing some options to > the kernel at boot time and there is nothing harmful in doing that :-? Most of them are harmless. Some even make the error message go away. At least one of the suggestions (passing the option iommu=false) ist harmful though (disables USB). > I passed the link not because it provided a "magic solution" but for you > get an idea of the origin of that message and how to bypass it ;-) Yes, I agree. > I am not getting that message in dmesg (running lenny amd64, 8 GiB.) > *but* my BIOS has "memory reclaiming" enabled. Interesting. Intel CPU? Because in the forum whose link you posted, all the CPUs in people's signatures were (as far as I see) made by AMD. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkuj/ycACgkQ+VSRxYk4409zRQCggK2l7xS3F0Ii15Q3p2wF7PI9 UQYAoNnAXYD3PI/L3I7nn0e9xnxUSzd0 =hNyn -----END PGP SIGNATURE----- -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org Archive: http://lists.debian.org/4BA3FF27.6000008(a)web.de
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