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xen-devel
Re: [Xen-devel] Different esps
> On Tue, 2004-01-20 at 15:42, Jacob Gorm Hansen wrote:
> > On Tue, 2004-01-20 at 13:25, Steven Hand wrote:
> > > > On Tue, 2004-01-20 at 12:11, Jacob Gorm Hansen wrote:
> > >
> > > Anyway, can you post -
> > >
> > > a) what it is you're trying to do in detail (I'm guessing it's
> > > to do with migration but not sure what stage you're at) and
>
>
> This is my recovery function, which eip points to when the new domain is
> started:
>
> static void recover(void)
> {
> __cli();
> HYPERVISOR_stack_switch(__KERNEL_DS, current->thread.esp0);
> asm volatile("addl $0x0, -4(%%eax)" : :"eax"(current->thread.esp0));
> while(1) HYPERVISOR_console_write("alive",5);
>
> ...
>
> I touch the ring1 stack to make sure it is writeable (due to my
> migration hacks it may not always be).
>
> The output on the serial looks like below. The first four lines are
> printed by my version of Xen as a response to SCHEDOP_exit:
>
> exit dom 41 : esp1 c3a96000, ss 00000821
> eip c00b5b6d esp c3a95ed8 eflags 296
> Killing domain 41
> Releasing task 41
> DOM42: alive
> DOM42: alive
> DOM42: alive
> DOM42: alive
> DOM42: alive
> DOM42: alive
> DOM42: alive
> DOM42: alive
> DOM42: alive
> DOM42: alive
> DOM42: alive
> DOM42: alive
> DOM42: alive
> fault_in_hypervisor 2
> dom 42 : esp1 c3a96000, ss 00000821
> eip 00000000 esp c3a92004 eip 00000000 pf-addr c3a91ff8 eflags 10286
> Killing domain 42
> Releasing task 42
>
> As you can see, the crash is not happening in direct response to some
> action in the domain, but rather as an effect of something happening
> outside. I was speculating that perhaps I need to re-register for the
> timer interrupt, or that the __cli() does not prevent Xen from trying to
> deliver them?
The __cli() should certainly prevent any events from being delivered.
It's tricky to work out what the above means as you've clearly hacked
Xen to e.g print "fault_in_hypervisor 2" (is 2 the error_code? is
there any reason you've added this stuff in place of the regular code
in do_trap() or do_page_fault()?). Can you post the code/diffs for
these parts of xen?
What is at 0xc3a91ff8? Have you actually taken a page fault? I note
that zero eips are not so good -- but OTOH I don't know what those
values you print actually are [partic given there are two eips]...
plus if we're really multiply faulting in the hypervisor, all bets
may well be off...
cheers,
S.
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