[PATCH v2 4/4] arm64: Add support for binary image files

Geoff Levand geoff at infradead.org
Thu Jul 28 11:04:43 PDT 2016

Hi Pratyush,

On Thu, 2016-07-28 at 09:31 +0530, Pratyush Anand wrote:
> On 26/07/2016:08:18:57 PM, Geoff Levand wrote:

> You removed page_offset calculation in rework.
> I am unable to understand that how arm64_mem.page_offset will be filled up now
> for binary image case.
> I think, we still need to keep page_offset user input. 

The current kernel linker scripts are setup to output virtual
address values to the vmlinux elf file.  

To load the elf sections of vmlinux using the provided elf
file loader, elf_exec_load(), we need to convert those elf
header values to physical addresses since we work with
physical addresses in the kernel's kimage structure.

That conversion is 

  p = v - page_offset + phys_offset;

We get phys_offset from the memory ranges, and we calculate
page_offset from the elf header info.

As for the binary image file, we load that with
add_segment_phys_virt(), which can put the binary data of the
Image file into memory at a physical address we specify:

  image_base = phys_offset + text_offset.

phys_offset is again from the memory ranges, and text_offset
from the arm64 image header.

> You may take following
> two patches which does this, or you may leave binary image support patch which I
> will send after your patches are merged.
> https://github.com/pratyushanand/kexec-tools/commit/5b7e49a75d1d6cd4ac846f50ff10275fd54cb545

This one may be useful, for debugging if anything.

> https://github.com/pratyushanand/kexec-tools/commit/a0ce0ce673755c4061c1f081170a3a75dfa1d1fb

We do not need, nor want, a PAGE_OFFSET option.


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