Re: [EDK DEV] Mapping memory in runtime driver

Subject: Re: [EDK DEV] Mapping memory in runtime driver

From: Randy Thelen <rthelen@vmware.com>

To: "dev@edk.tianocore.org" <dev@edk.tianocore.org>

Date: 2008-07-22 22:59:24

Martin Mocko wrote:

> I am doing it on 64-bit version of UEFI, where identity mapping for  
> memory used by UEFI is enabled, and thus i also need some functrion  
> to map
> areas that i want to touch.

I presume you mean Itanium, i.e., Ipf.  In that case, you might want  
to dig into the processor architecture to find the address space  
that's carved out for privileged code to access raw addresses.

The Intel Itanium Architecture Manuals, Volume 2: System Architecture  
states that the upper 3 bits of any virtual address are the VRN:  
virtual region number.  I don't know which VRN refers to physical 1:1  
addressing, but I'm quite sure there is one lying around.  Once you  
find that you should be good to go.

> Unless UEFI would somehow identity-map ALL memory, but somehow i  
> doubt that (mapping table would be huge)

To short circuit the mapping table, the VRNs are used; if I understand  
correctly.

-- Randy


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