On Tue, May 15, 2012 at 4:30 AM, Henrique de Moraes Holschuh <h...@debian.org > wrote:
> On Mon, 14 May 2012, Stan Hoeppner wrote: > > On 5/13/2012 7:02 PM, Henrique de Moraes Holschuh wrote: > > > On Fri, 11 May 2012, Seyyed Mohtadin Hashemi wrote: > > >> On 5/10/2012 1:16 PM, Stan Hoeppner wrote: > > >>> If this doesn't fix the issue, and memtest and other utils can see > all > > >>> 64GB just fine, then I'd say you're dealing with a BIOS bug. > > >> > > >> The very top of /var/log/dmesg has the kernel debug output about the > memory > > >> map. It might well tell us very quickly who is the culprit, if the > user > > >> with the problem can post it for the best working case and the > non-working > > >> [ 0.000000] e820 update range: 00000000e0000000 - 000000101f000000 > > >> (usable) ==> (reserved) > > >> [ 0.000000] WARNING: BIOS bug: CPU MTRRs don't cover all of memory, > > >> losing 61936MB of RAM. > > > > > > There you have it. > > > > I'm not surprised I was correct WRT a BIOS bug, but I am a little > > embarrassed I didn't know and suggest this would be reported in dmesg. > > I admit I just don't see this very often--this being the 1st time > > actually seeing this WARNING. > > Well, it is the first time I've seen a BIOS screw it up so badly as to > have someone lose 61GiB of RAM over it. > > > > Any of the latest versions of the longterm kernels (2.6.32, 3.0), or > > > latest 3.2 should be able to repair MTRRs properly, but you have to > > > compile the kernel with that option enabled. It might be already > > > available, but not enabled by default. In that case, this might help > > > you: > > > > Yep. In vanilla 3.2.6 it's selected by default in menuconfig, and you > > can't un-select it. > > We _really_ need to have that enabled by default on the Debian kernels > IMO, if we don't enable it already. > > -- > "One disk to rule them all, One disk to find them. One disk to bring > them all and in the darkness grind them. In the Land of Redmond > where the shadows lie." -- The Silicon Valley Tarot > Henrique Holschuh > Thank you for the tips Henrique and Stan, unfortunately i don't have time to build/test new kernels this week because i have to finish my thesis. I will have time next week to look at it and report back the results. best regards, Mohtadin
