Messages in this thread | | | Date | Mon, 4 Jun 2007 08:48:37 -0700 | From | "Ray Lee" <> | Subject | Re: Intel's response Linux/MTRR/8GB Memory Support / Why doesn't the kernel realize the BIOS has problems and re-map appropriately? |
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On 6/4/07, Jesse Barnes <jbarnes@virtuousgeek.org> wrote: > On Sunday, June 3, 2007 2:15:06 Matt Keenan wrote: > > Justin Piszcz wrote: > > > On Sat, 2 Jun 2007, Andi Kleen wrote: > > >>> I feel, having a silent/transparent workaround is not a good idea. > > >>> With that > > >> > > >> If enough RAM is chopped off users will notice. They tend to complain > > >> when they miss RAM. I don't like panic very much because for many > > >> users it will be a show stopper (even when they are not blessed > > >> with "quiet" boots like some distributions do) > > >> > > >> The message in dmesg could be also emphasized a bit with a little > > >> ASCII art (but no <blink> tag in there) > > >> > > >> The problem I'm more worried about is if the system will be really > > >> stable --- could it be that the memory controller is still > > >> misconfigured and cause other stability issues? (we've had such > > >> cases in the past). Also I'm not sure we can handle the case of > > >> the MTRR wrong not at the end of memory but at the hole sanely. > > >> > > >> -Andi > > > > > > So far I have been booting with mem=8832M and have run stress/loaded > > > the memory subsystem pretty good; what other tests should I run? > > > > > > It'd be nice if we could pose some sort of solution/warning for the > > > future so other people do not have to experience the same problems. > > > > > > What are the next steps? > > > > Wouldn't it be possible for the e820/MTRR set up code detect the problem > > and suggest a mem=xxxx that would fix the problem (while also > > complaining that the BIOS is broken)? > > Yes, that should be fairly easy, though as Andi points out, if there are holes > in the MTRR setup, things get a little trickier (I had an earlier patch to > deal with this, but ended up with too many early boot issues). > > Maybe what Venki suggested would be best: just detect the condition and > panic, with a string telling the user to use mem=xxx (we can figure that out) > and/or upgrade their BIOS.
Ick. Systems that used to boot fine would then panic on a kernel upgrade. That's rather rude for a condition that's merely an optimization (using all memory), rather than one of correctness. A panic seems entirely inappropriate.
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