Re: [Xen-devel] Help With Custom Hyper Calls

[Tim Deegan <tim@xxxxxxx>]

Hi, 

Please don't top-post. 

At 10:00 -0500 on 15 Aug (1313402441), John Backes wrote:
> I changed the table entries in both xen/arch/x86/x86_32/entry.S and
> xen/arch/x86/x86_64/entry.S. 

Yes; you also need to edit xen/arch/x86/x86_64/compat/entry.S 

> Could you point me towards these existing
> kernel mechanisms for issuing hypercalls? Thanks.

In linux: arch/x86/include/asm/xen/hypercall.h 

Cheers,

Tim.

> On 08/15/2011 09:56 AM, Tim Deegan wrote:
> > At 09:45 -0500 on 15 Aug (1313401506), John Backes wrote:
> >> So I greped through the s
> >>
> >> I've altered the hypercall_table and hypercall_args_table to have an
> >> additional entry in xen/arch/x86/x86_32/entry.S and in
> >> xen/arch/x86/x86_64/entry.S:
> >>
> > 
> > You also need to edit xen/arch/x86/x86_64/compat/entry.S, for the case
> > where Xen is 64-bit and dom0 kernel is 32-bit. 
> > 
> >> static int hyper_init(void){
> >>
> >>   int output;
> >>
> >>   printk(KERN_ALERT "Testing Hypercall\n");
> >>
> >>   __asm__ ( "movl $39, %%eax;"
> >>             "int $0x82;"
> >>           : "=a" (output)
> >>           );
> > 
> > While this should work, you probably ought to be using the hypercall
> > page (and the existing kernel mechanisms) to make hypercalls. 
> > 
> >>   return SUCCESS;
> >> }
> >>
> >> static void hyper_exit(void){
> >>   printk(KERN_ALERT "Removing Hypercall Module");
> >>
> >>
> >> }
> >>
> >> module_init(hyper_init);
> >> module_exit(hyper_exit);
> >> ...........................
> >>
> >> I then run "xm dmesg" to see if I can see the "NEW HYPERCALL RECEIVED"
> >> message, but nothing appears.  Any thoughts?
> > 
> > You could print the return value from the hypercall in your module?
> > 
> > Tim.
> > 

-- 
Tim Deegan <tim@xxxxxxx>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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