On Monday 25 April 2005 10:31, Andree Leidenfrost wrote: > Hi Paolo > > Thanks a lot for your response and suggestions! I think the handling of > the fpx registers' absence is the key - see attached patch. But please > read on... > > On Sun, 2005-04-24 at 17:12 +0200, Blaisorblade wrote: > > 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). ;-) > > > > [...] > > 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. > > I have "CONFIG_STDERR_CONSOLE=y" in .config. Running: > > emden2:/home/fwumlusr# ./linux-2.6.11-bs4 stderr=1 mem=32M > ubd0=./fwumlfs.img con=pts eth1=tuntap,tap1 > Checking for /proc/mm...found > Checking for the skas3 patch in the host...found > > still only gives the previous two lines of output unfortunately. > > > [...] > > Is there any difference in the host distro? > > Nope, it's Debian Sarge on both the VIA and the Athlon64 box updated > daily. > > > > 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).
> Excellent point! I've done that and am getting this: Hmm, what a foolish I am! Luckily I posted the suggestion even if it seemed stupid... Uml is full of errors like that, sadly (you don't see them at a glance). I just sent it for merging. > init_registers BELOW ZERO: have_fpx_regs=0, err=-1, errno=5, EIO=5 > So, the value of have_fpx_regs is correct but the 'if' clause checks > (err != EIO) which is not correct according to the ptrace manpage and > the above values: ptrace always returns -1 on error, the actual cause is > provided via errno. > My attached little patch 'no_fpx_regs_handling.patch.gz' fixes this. > With this patch applied, UML starts up fine on my VIA box. The patch is > against vanilla linux 2.6.11. It would be great if it could get included > upstream. > > What I don't understand, though, is why panic didn't just kill the > process rather than spinning in some endless loop. Any ideas? Not really... panic on a real box *is* a spinning loop, but UML tricks it the other way. The two possible problems here are: 1) The panic text does not go to the console: maybe it's too early, maybe it's the console code problems (which I'm already solving, I'm not rushing on them since the change is invasive). 2) The "tricks" has not been done yet. Actually, the first problem should also affect the printk, but hey, it's a bit randomical (the console is not flushed on exit). > From what I've read elsewhere, CMOV is not part of Intel's PentiumPro > spec although Intel's PentiumPro implements it. So, the Samuel 2 is a > true PentiumPro clone according to the specs but not in practice. One question: when I'll allow to optimize UML for the processor it runs on (like you do in i386 configuration), are you going to test the result? I don't think I'll find anybody else with this config... -- 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
