[Xen-devel] question about the meaning of auto-translated mode and no overlay mode

[tgh <tianguanhua@xxxxxxxxxx>]

hi
I try to understand the code of xen memory ,and I am confused  about  
the  memory-management modes,could someone help me
there are gmfn, gpfn and pfn  in the xen ,and in the 
/xen/include/xen/mm.h  there are some explanation about them as follows:
* 1. gpfn/gpaddr: A guest-specific pseudo-physical frame number or address.
* 2. gmfn/gmaddr: A machine address from the p.o.v. of a particular guest.
* 3. mfn/maddr:   A real machine frame number or address.
* 4. pfn/paddr:   Used in 'polymorphic' functions that work across all
*                 address spaces, depending on context. See the pagetable
*                 conversion macros in asm-x86/page.h for examples.
*                 Also 'paddr_t' is big enough to store any physical 
address.
*

I seems to understand the meaning about them,but I am confused about  
the different memory-management modes as follows
* This scheme provides consistent function and variable names even when
* different guests are running in different memory-management modes.
* 1. A guest running in auto-translated mode (e.g., 
shadow_mode_translate())
*    will have gpfn == gmfn and gmfn != mfn.
* 2. A paravirtualised x86 guest will have gpfn != gmfn and gmfn == mfn.
* 3. A paravirtualised guest with no pseudophysical overlay will have
*    gpfn == gpmfn == mfn.
*

what is the meaning about auto-translated mode,is it not the same with 
paravirtualised one ?
does the auto-translated mode work for hvm and shadow mode? how does it 
work?
and what is the mechanism about paravirtualised guest with no 
pseudophysical overlay?
I am confused about it

could you help me
Thanks in advance

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