Messages in this thread | | | From | Jesse Barnes <> | Subject | Re: Intel's response Linux/MTRR/8GB Memory Support / Why doesn't the kernel realize the BIOS has problems and re-map appropriately? | Date | Mon, 4 Jun 2007 08:40:21 -0700 |
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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.
I'll spin a new patch to do that today.
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