Physical memory allocation to L4linux

Masti Ramya Jayaram rmasti at inf.ethz.ch
Tue Sep 16 07:57:16 CEST 2014


Hey Adam,

Yes I can confirm that I was a able to trace the code from fpage_map() to map() but I see zero addresses there - i.e. When I check the receiver and sender addresses and size everything is zero. This was despite it being correct until the handle_sigma0_request() function in mem_map.cc. So I just assumed I was looking in the wrong place.

I will try to dig a little more and check. 

Sent from my phone

> On 15 Sep 2014, at 23:55, "Adam Lackorzynski" <adam at os.inf.tu-dresden.de> wrote:
> 
> Hi,
> 
>> On Mon Sep 15, 2014 at 18:25:37 +0000, Masti  Ramya Jayaram wrote:
>> Thanks for the input. I will try changing one of the suggested functions. 
>> 
>> It would be great out of curiosity if you could elucidate why the following occurs.  
>> 
>> I see that there is a new iomem region being created and this happens
>> only when I try to read from the mapped region - not until then. But
>> none of this reaches the kernel or maybe I am not sure where to look..
> 
> Well, it should reach the kernel. For sigma0 mappings appear out of
> nothing (it's the root), so you should at least see it in the mapping
> loop in map_util.cpp's map() function (also see the comments on sigma0
> there). 
> 
>> In fact, I see that the init_mem file parses the kernel  memory
>> descriptors to find the regions. So under what circumstances does
>> sigma0 go back to the kernel for mem/io?
> 
> In this case there a fpage is created that is used in the reply to the
> client which will then create the mapping.
> 
> 
> 
> Adam
> -- 
> Adam                 adam at os.inf.tu-dresden.de
>  Lackorzynski         http://os.inf.tu-dresden.de/~adam/
> 
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