On Sunday 24 April 2005 05:20, Andree Leidenfrost wrote: > Hi all > > I've been banging my head against this one for a while now, so I finally > figured I could do with some help (and it might even be a bug in > UML). ;-)
> I am trying to set up a 2.6 UML instance on a VIA C3 Samuel2 [1] based > system running a freshly installed Debian Sarge. In TT mode, everything > works fine. However, in SKAS mode, the guest kernel starts up and > outputs only: > Checking for /proc/mm...found > Checking for the skas3 patch in the host...found Can you add stderr=1 to the boot process (after enabling the stderr console in the configuration)? There's possibly some kernel message stuck in the buffers. > then nothing happens, but the guest kernel process uses 100% of the CPU. > The same setup works fine on my Athlon64 system (IA32 mode) with > identical host and guest kernels. Is there any difference in the host distro? > I am not sure whether it provides additional insight, but here is the > strace on the VIA box: > ptrace(PTRACE_GETFPXREGS, 7197, 0, 0xa02aac80) = -1 EIO (Input/output > error) Well, this one *is* strange. And yes, it's specific to your processor (it happens because the "fxsr" CPU feature is missing, as reported by /proc/cpuinfo). However, the UML code seems prepared to cope with this (see arch/um/os-Linux/sys-i386/registers.c, in init_registers; maybe you can add some printk's to verify that have_fpx_regs is actually set to 0). For the rest I've not checked, but I've not seen anything strange. > (The SIGINT towards the end is me killing the guest kernel with Ctrl-C.) > The above is with skas3-v9-pre1 [2] for the host and bs4 for the guest > kernel which were applied to Debian's 2.6.11 sources. > I've tried this with 2.6.10 and 2.6.11 kernels, both Debian and vanilla > with and without the bs patch, all with the same result. I've tried > compiling both the host and guest kernel on the VIA box, with no > difference. The guest kernel is compiled with "ARCH=um SUBARCH=i386", so > I hope I have excluded the CMOV on VIA C3 problem. No, SUBARCH=i386 does not do any difference, if you build on a x86 system (it makes sense on a x86_64 one). Anyhow, the UML kernel has no specific optimization enabled for processors >= i386 (the cmov problem is probably for some root filesystems) > Also, the guest > kernel is statically linked, so it shouldn't have anything to do with > TLS either (I think). Hmm, yes, and beyond that TLS support on the host is well tolerated since many releases. The only problem can be with guests filesystems. > Any help would be hugely appreciated. Also, I am more than happy to run > additional tests and/or provide debugging information. (I've never done > kernel debugging, so a hint or two would certainly be great.) > Cheers > Andree > [1] /proc/cpuinfo: > processor : 0 > vendor_id : CentaurHauls > cpu family : 6 > model : 7 > model name : VIA Samuel 2 > fpu : yes > fpu_exception : yes > cpuid level : 1 > wp : yes > flags : fpu de tsc msr cx8 mtrr pge mmx pni 3dnow It hasn't cmov?? Well, I didn't expect this. Still, no problem with UML, as long as the root_fs you use is not compiled to expect cmov. And even then, the problem would be later. > bogomips : 1187.84 > [2] Patch skas-2.6.11-v8.patch.bz2 doesn't apply cleanly to neither > vanilla nor Debian 2.6.11 kernel for me, so I'm using > skas-2.6.11-v9-pre1.patch.bz2. The problem is the same with 2.6.10 using > skas-2.6.10-v8.patch.bz2, though. Well, v9-pre1 shouldn't create problems, but it's strange that -v8 does not apply to a vanilla kernel (for the Debian one it already can make a bit more sense). Here -v8 applies perfectly! Can you verify you were using a vanilla tree? Also, for -v8-rc5 (which is identical apart the version number) is *reported* to work on vanilla 2.6.11. -- Paolo Giarrusso, aka Blaisorblade Skype user "PaoloGiarrusso" Linux registered user n. 292729 http://www.user-mode-linux.org/~blaisorblade ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&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
