[ipxe-devel] memory usage in iPXE Legacy

Michael Brown mbrown at fensystems.co.uk
Thu Dec 5 15:34:37 UTC 2013

On 22/11/13 06:31, Lily_Wang at asus.com wrote:
> For some technical issue, I need to know the exact memory address range
> used by the iPXE legacy version. Or the memory usage algorithm.
> Could you please help me on this question?

It's not a trivial answer.  Once iPXE is up and running, there are three 
ranges in use:

- base memory text and data segments, placed according to the FBMS 
counter as per the PXE spec

- main iPXE binary, placed near the top of 32-bit address space, edited 
out of the system memory map

- any memory allocated using umalloc() (e.g. for downloaded images), 
placed immediately below the main iPXE binary, edited out of the system 
memory map.

There are many other parts of memory used temporarily in bootstrapping 
iPXE, particularly from ROM.


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