Re: hypercall_xlat_continuation()

[Mukesh Rathor <mukesh.rathor@oracle.com>]

Keir Fraser wrote:
> On 22/05/2009 22:58, "Mukesh Rathor" <mukesh.rathor@oracle.com> wrote:
> 
>> Ok. Even if I can't make it clearer, at least I'll add few lines of comments
>> explaining what's going on, after (and if) I figure it out.
>>
>> Jan,
>>
>> It seems assumption is made that a 64bit dom0 will not have a 32bit app making
>> hypercall?
>>
>> BUG_ON(*reg != (unsigned int)*reg);  <====
> 
> You know that all the 'xlat' stuff in Xen is for 32-bit guests running on
> 64-bit hypervisor, right? 64-bit dom0 would never execute this logic.

Unless someone like me, in trying to make 32bit apps on 64bit dom0 work, 
causes it to take compat path if it's 32bit hcall. Yeah, I know whacky :)...

Thanks as always,
Mukesh

PS: If anyone is curious, if the call is 32bit hcall, in entry.S I make it jmp 
   to compat/entry.S and do compat hcall. So far, other than this xlat stuff, 
seems ok! I set a register in dom0 to before hcall to indicate it's from a 
32bit app.