RE: [Xen-devel] Help? Red Hat fails, Suse/Debian both work fine

["Xu, Anthony" <anthony.xu@xxxxxxxxx>]

>It is likely some subtle difference (or bug), perhaps in mmap?

As I know, in Redhat, mmap can return NULL address, but seems xen
can't handle this situation, see below code segment:

In function vcpu_translate() of vcpu.c file

    else if (!region && warn_region0_address) {
        REGS *regs = vcpu_regs(vcpu);
        unsigned long viip = PSCB(vcpu,iip);
        unsigned long vipsr = PSCB(vcpu,ipsr);
        unsigned long iip = regs->cr_iip;
        unsigned long ipsr = regs->cr_ipsr;
        printk("vcpu_translate: bad address %p, viip=%p, vipsr=%p, iip=%p, 
ipsr=%p continuing\n", address, viip, vipsr, iip, ipsr);
    } 
warn_region0_address is turned off by default,
so maybe we can turn on warn_region0_address to see whether this is the root 
cause.

Thanks,
-Anthony 

>-----Original Message-----
>From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
>[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Magenheimer, Dan
>(HP Labs Fort Collins)
>Sent: 2006年3月1日 5:45
>To: xen-devel
>Cc: yo.fujita; Akio Takebe; xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>Subject: [Xen-devel] Help? Red Hat fails, Suse/Debian both work fine
>
>Hi all --
>
>We are seeing a strange problem where a recent cset causes
>Red Hat to fail domU boot on ia64 complaining of a hotplug
>problem but doesn't cause any problem for Suse or Debian.
>It is likely some subtle difference (or bug), perhaps in mmap?
>Suggestions/advice from anyone more familiar with distro
>differences (on ia64) would be appreciated.
>
>Changeset is xen-unstable 8783 ("Use /dev/kmem to map dom0
>xenstore page instead of abusing the foreign mapping interface.",
>Feb 8, committed by Christian).  Backing out this changeset
>or using the small patch below causes the problem to go away,
>so we have a workaround, but a root cause would be nice
>to know and fix.
>
>Full thread of discussion can be found here:
>http://lists.xensource.com/archives/html/xen-ia64-devel/2006-02/msg00104
>.html
>
>Thanks,
>Dan
>
>> -----Original Message-----
>> From: Akio Takebe [mailto:takebe_akio@xxxxxxxxxxxxxx]
>> Sent: Tuesday, February 28, 2006 2:47 AM
>> To: Magenheimer, Dan (HP Labs Fort Collins); yo.fujita;
>> xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>> Cc: Akio Takebe
>> Subject: RE: [Xen-ia64-devel] Weekly benchmark results [2/3rd week]
>>
>> Hi, Dan
>>
>> I'm still debuging, but it is very difficult...
>> Much advice is welcome. :-)
>>
>> Now I can boot domU by using the following patch.
>>
>> diff -r 6c43118bdba8 tools/xenstore/xenstored_domain.c
>> --- a/tools/xenstore/xenstored_domain.c Fri Feb 24 15:41:08 2006 -0700
>> +++ b/tools/xenstore/xenstored_domain.c Tue Feb 28 18:20:16 2006 +0900
>> @@ -467,6 +467,7 @@ static int dom0_init(void)
>>         int rc, fd;
>>         evtchn_port_t port;
>>         unsigned long kva;
>> +       unsigned long mfn;
>>         char str[20];
>>         struct domain *dom0;
>>
>> @@ -500,9 +501,16 @@ static int dom0_init(void)
>>         if (fd == -1)
>>                 return -1;
>>
>> -       dom0->interface = mmap(NULL, getpagesize(),
>> PROT_READ|PROT_WRITE,
>> -                              MAP_SHARED, fd, kva);
>> -       if (dom0->interface == MAP_FAILED)
>> +       mfn=((0x0fffffffffffffff & kva) >>14);
>> +/*
>> +        dom0->interface = mmap(NULL, getpagesize(),
>> PROT_READ|PROT_WRITE,
>> +                               MAP_SHARED, fd, kva);
>> +*/
>> +       dom0->interface = xc_map_foreign_range(
>> +               *xc_handle, 0,
>> +               getpagesize(), PROT_READ|PROT_WRITE, mfn);
>> +       if (!dom0->interface)
>> +//     if (dom0->interface == MAP_FAILED)
>>                 goto outfd;
>>
>>         close(fd);
>>
>> Best Regards,
>>
>> Akio Takebe
>>
>> >Hi Akio --
>> >
>> >Any more progress on this issue?  If you are stuck,
>> >maybe we should post the problem to xen-devel to
>> >see if we can get help from a Red Hat person (since
>> >the problem doesn't occur on Suse or Debian).
>> >
>> >Thanks,
>> >Dan
>> >
>> >> -----Original Message-----
>> >> From: Akio Takebe [mailto:takebe_akio@xxxxxxxxxxxxxx]
>> >> Sent: Thursday, February 23, 2006 8:45 PM
>> >> To: Magenheimer, Dan (HP Labs Fort Collins); yo.fujita;
>> >> xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>> >> Cc: Akio Takebe
>> >> Subject: RE: [Xen-ia64-devel] Weekly benchmark results [2/3rd week]
>> >>
>> >> Hi, Dan and Alex
>> >>
>> >> I think this issue is only on ia64.
>> >> I seem that kmem_map@drivers/char/mem.c is used on ia64,
>> >> but mem_map@drivers/xen/char/mem.c is used on x86.
>> >> So I think pfn or kva aren't set correctly.
>> >> We tried to boot domU with revesing cset xen-ia64-ustable.8790
>> >> and it was good work.
>> >>
>> >> I'm still debugging it. :-<
>> >>
>> >> Best Regards,
>> >>
>> >> Akio Takebe
>> >>
>> >> >Confirmed cset xen-unstable 8783 fails while 8782 succeeds.
>> >> >
>> >> >Perhaps there's something different about mmap on RH
>> >> >vs Suse and Debian?  Perhaps only on ia64?
>> >> >
>> >>
>> >>
>> >>
>>
>>
>>
>
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