[PATCH 00/19] PBL: Add PBL ELF loading support with dynamic relocations

[Ahmad Fatoum]

Hi,

On 1/5/26 17:47, Sascha Hauer wrote:
> On Mon, Jan 05, 2026 at 03:08:03PM +0100, Ahmad Fatoum wrote:
>> Hi,
>>
>> On 1/5/26 12:26 PM, Sascha Hauer wrote:
>>> Until now we linked the raw barebox proper binary into the PBL which
>>> comes with a number of disadvantages. We rely on self-modifying code
>>> to in barebox proper (relocate_to_current_adr()) and have no initialized
>>> bss segment (setup_c()). Also we can only mark the .text and .rodata as
>>> readonly during runtime of barebox proper.
>>>
>>> This series overcomes this by linking a ELF image into the PBL. This
>>> image is properly layed out, linked and initialized in the PBL. With
>>> this barebox proper has a proper C environment and text/rodata
>>> protection from the start.
>>>
>>> As a bonus this series also adds initial MMU support for RISCV, also
>>> based on loading the ELF image and configuring the MMU from the PBL.
>>>
>>> This series also marks my start into AI assisted programming as you can
>>> see in the Co-Authored-By: Claude Sonnet 4.5 <noreply at anthropic.com>
>>> and 🤖 Generated with [Claude Code](https://claude.com/claude-code)
>>> tags. Without it I wouldn't have started this series during my xmas
>>> break, but with it it was actually quite fun to do; it felt like having
>>> a programming team which I just had to delegate new tasks to while
>>> having fun with my family myself ;)
>>
>> Did you do size comparisons to determine how much this series affects
>> binary size? I found that compressing every segment separately resulted
>> in a smaller binary size even after addition of ELF parsing to PBL, but
>> I used a purpose-built ELF loader unlike to what you did here.
> 
> I did now.
> 
> ARM64 barebox-dt-2nd.img raw:  1246506
> ARM64 barebox-dt-2nd.img ELF:  1248892 (+ 2386 bytes)
> ARM32 barebox-dt-2nd.img raw:  1217036
> ARM32 barebox-dt-2nd.img ELF:  1219159 (+ 2123 bytes)
> 
> With --strip-section-headers instead of --strip-debug --strip-unneeded
> the last image goes down to 1217940 bytes, so only 904 bytes size
> increase.

Is the raw image from before the series was applied, so we can judge the
total size increase?

I redid tests for my series, but this time in the same build directory and
got values similar to yours:

ARM64 barebox-dt-2nd.img before: 992276
ARM64 barebox-dt-2nd.img after:  993029 (+ 753 bytes)

Previous measurement of ELF compression being smaller must have been
a mistake it seems.

Cheers,
Ahmad


> 
> Sascha
> 


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