Date: Wed, 01 Jun 2011 11:36:32 +0200 From: Sergi <sergi@estrafolari.com> To: Kostik Belousov <kostikbel@gmail.com> Cc: freebsd-xen@freebsd.org Subject: Re: fpudna: fpcurthread == curthread XXXX times Message-ID: <4DE60820.1080409@estrafolari.com> In-Reply-To: <20110601082156.GB48734@deviant.kiev.zoral.com.ua> References: <4DE5EDD7.20105@estrafolari.com> <20110601082156.GB48734@deviant.kiev.zoral.com.ua>
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On 01/06/11 10:21, Kostik Belousov wrote: > On Wed, Jun 01, 2011 at 09:44:23AM +0200, Sergi wrote: > >> Hello, >> >> I'm working with full virtual FreeBSD 8.2-RELEASE-p1 domU under debian >> squeeze and xen-hypervisor-4.0-amd64. >> >> If I cfg this hvm with cpu> 4 : >> >> vcpus = 5 >> >> these messages block the server : >> >> fpudna: fpcurthread == curthread XXXX times >> >> The machine is pingable but I'm unable to ssh to it. >> >> On single user it works fine, fsck an so on ok, but when switching to >> multiuser these fpudna messages start flooding. >> >> I've googled but haven't found anything; something from 2005 about fpudna : >> >> http://lists.freebsd.org/pipermail/freebsd-amd64/2005-April/004413.html >> >> and this link, but I don't have the options he mentions enabled on the >> kernel : >> >> http://forums.freebsd.org/showthread.php?t=17979 >> >> Has anyone stepped on this behaviour before?, is there any workaround? >> The machine really seems to detect cpu's available and responds to keyboard >> on VNC, but it's impossible to see whats written down because of the >> messages flooding the screen. >> > You did not specified the architecture of the domu. From the message, I can > guess that your guest is running amd64 kernel. There are slight differences > in the handling of the FPU in i386 and amd64 that may matter there. > > The message you reported means that the FreeBSD kernel assumes that FPU > is currently loaded with the context of the current thread, but the > CR0.TS bit is set, meaning that FPU context is set for switch. > > AFAIR, HVM means that you run bare-metal kernel, right ? Most likely, > it is some issue with Xen itself. I am curious whether the following > will cause any usermode-visible regression for you: > > diff --git a/sys/amd64/amd64/fpu.c b/sys/amd64/amd64/fpu.c > index 08e5e57..a5ee853 100644 > --- a/sys/amd64/amd64/fpu.c > +++ b/sys/amd64/amd64/fpu.c > @@ -394,14 +394,8 @@ fpudna(void) > struct pcb *pcb; > > critical_enter(); > - if (PCPU_GET(fpcurthread) == curthread) { > - printf("fpudna: fpcurthread == curthread %d times\n", > - ++err_count); > - stop_emulating(); > - critical_exit(); > - return; > - } > - if (PCPU_GET(fpcurthread) != NULL) { > + if (PCPU_GET(fpcurthread) != NULL&& > + PCPU_GET(fpcurthread) != curthread) { > printf("fpudna: fpcurthread = %p (%d), curthread = %p (%d)\n", > PCPU_GET(fpcurthread), > PCPU_GET(fpcurthread)->td_proc->p_pid, > Hello, yes, sorry, amd64, and yes, hvm hardware virtual machine, not paravirtual. So, you mean patching fpu.c and recompiling the kernel, right?, I'm new to modifiying src files. Thanks for your help, Sergi
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