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? > 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. Since the machine only has 1G of RAM, HIGHMEM wasn't enabled, as I understood from the kconfig description it wasn't necessary unless I had more than 1G of RAM. Changing to HIGHMEM4G on the host doesn't solve the problem though. The current host config is: [EMAIL PROTECTED]:~$ egrep '(HIGHMEM|SMP|3_LEVEL_PGTABLES)' /boot/config-`uname -r` # CONFIG_X86_BIGSMP is not set CONFIG_SMP=y # CONFIG_NOHIGHMEM is not set CONFIG_HIGHMEM4G=y # CONFIG_HIGHMEM64G is not set CONFIG_HIGHMEM=y CONFIG_X86_FIND_SMP_CONFIG=y CONFIG_X86_SMP=y 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? Does BROKEN_ON_SMP=y or SMP not being set on the guest conflict with SMP=y on the host? Thanks again for your help. -- Ruaidhri ------------------------------------------------------- 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
