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

[John Backes <john.backes@xxxxxxxxxxxxxxxxx>]

I changed the table entries in both xen/arch/x86/x86_32/entry.S and
xen/arch/x86/x86_64/entry.S.  Could you point me towards these existing
kernel mechanisms for issuing hypercalls? Thanks.

- John

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.
> 

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