On Friday 22 July 2005 18:53, Ruaidhri Power wrote: > On Thu, Jul 21, 2005 at 01:23:46AM +0200, Blaisorblade wrote: > > Which was the old UML version? Which is your guest distro? > > Also, have you tested the old UML releases on this new host kernel > > version? Since UML address space is getting shrinked down to 32M, I fear > > address space randomization (introduced in 2.6.12) may be playing a role.
> It looks like VA space randomization is the culprit. The problem only > shows up when the host is 2.6.12, and can be solved by setting the > kernel.randomize_va_space sysctl to zero. Thanks for the pointer there. > > > Kernel virtual memory size shrunk to 32505856 bytes > > Ok, here it's going to use just 32M of kernel memory rather than 768M... > > Did it happen even before? > I hadn't noticed that before, not sure what the problem is there. That > figure is actually 31M rather than 32M - does that give a clue to the > cause? Doesn't this disappear when shutting off address space randomization? > > Another thing to check is if you have changed some UML config option when > > recompiling, like for instance HIGHMEM or SMP or 3_LEVEL_PAGETABLES. > The host is a uniprocessor Pentium 4 without HT, but I've enabled > CONFIG_SMP because I want to use the same kernel on another machine > which does have HT. Unfortunately I don't have a copy of the old kernel > configs used, before I started using kernel-package to make the kernels. I don't care about the host, it's just UML to have problems with SMP and/or HIGHMEM. Mainly, Uml is very slow with HIGHMEM, and doesn't need it a lot, especially in SKAS mode... > And on the guest: > [EMAIL PROTECTED]:~$ linux --showconfig | egrep > '(HIGHMEM|SMP|3_LEVEL_PGTABLES)' # CONFIG_3_LEVEL_PGTABLES is not set > # CONFIG_SMP is not set > CONFIG_HIGHMEM=y > CONFIG_BROKEN_ON_SMP=y > Kconfig says "Three-level pagetables will let UML have more than 4G of > physical memory", so I guess I don't need that? Exactly - and they're mainly for x86-64 guests. > Does BROKEN_ON_SMP=y It's an internal thing, don't care - it is used to disable everything which is known "not to work" on SMP, for instance for locking issues. > or SMP not being set on the guest conflict with > SMP=y on the host? Not at all... they're totally indipendent - any combination of them should work - actually SMP on the guest is a bit unstable. -- Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!". Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894) http://www.user-mode-linux.org/~blaisorblade ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click _______________________________________________ User-mode-linux-user mailing list User-mode-linux-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user
