[Xen-ia64-devel] RE: vcpu_translate issue

["Magenheimer, Dan (HP Labs Fort Collins)" <dan.magenheimer@xxxxxx>]

> Dan,
> 
> I just want to run some testcases like ltp to make dom0 more 
> stable.

Understood.  That is good.  Every bit of testing helps to find
bugs (and you found one with ltp mmap09).

> If this is the case I have no choice but to defer those tests.

Can you temporarily turn off mmap09 to see if there are
other failures?  Or maybe you would like to try coding
up the patch from the pseudo-code below?

Thanks,
Dan

> >-----Original Message-----
> >From: Magenheimer, Dan (HP Labs Fort Collins) 
> [mailto:dan.magenheimer@xxxxxx]
> >Sent: 2005年11月4日 22:13
> >To: Xu, Anthony
> >Cc: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> >Subject: RE: vcpu_translate issue
> >
> >The warning is there because the current code doesn't yet
> >work properly for a region 0 virtual address.  Even
> >if you remove the printf, I don't think ltp mmap09 will
> >work properly because the current code assumes
> >incorrectly that every region 0 access is a guest
> >physical access.  Bug!  I think this is the first time
> >we have seen a region 0 virtual address.
> >
> >Also, the printf is very good at catching problems when
> >there is a new bug in Xen so it would be nice to
> >keep the printf.  Perhaps it could be tied to a
> >Xen command line option: warnregion0.  E.g.
> >
> >if (metaphysical) {
> >     if (address >> 61)
> >             panic_domain(("bad metaphysical address")
> >     else {
> >             ... existing phys translate code
> >     }
> >{
> >else if (!(address >> 61) && warnregion0) {
> >     printf
> >}
> >
> >I think this code will also fix region 0 virtual addresses
> >(because it properly falls through to the rest of
> >vcpu_translate).
> >
> >> -----Original Message-----
> >> From: Xu, Anthony [mailto:anthony.xu@xxxxxxxxx]
> >> Sent: Friday, November 04, 2005 3:20 AM
> >> To: Magenheimer, Dan (HP Labs Fort Collins)
> >> Cc: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> >> Subject: vcpu_translate issue
> >>
> >> Dan,
> >>
> >> In vcpu_translate function, if guest address is within region
> >> 0 and guest is in virtual mode, vcpu_translate will print
> >> warning message and don't translate. It seems you assume
> >> guest will not access this kind of address, but actually
> >> guest application can allocate region 0 address spaces by
> >> using system call mmap.
> >>
> >> You can try testcase mmap09 of ltp on both native and xen0 to
> >> find out this.
> >>
> >> So, Can we remove this code segment in vcpu_translate?
> >>
> >> Thanks,
> >> Anthony.
> >>
> >>
> 

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