Add elf-symbols project update

content/this-month/2026-06/index.md

@@ -87,9 +87,53 @@ In this section, we describe updates to Rust OS projects that are not directly r
     ...<<your project updates>>...
 -->
 
-<span class="gray">No projects updates were submitted this month.</span>
+### [`mkroening/elf-symbols`](https://github.com/mkroening/elf-symbols)
+<span class="maintainers">(Section written by [@mkroening](https://github.com/mkroening))</span>
+
+When developing an OS, you often need some information about the loaded kernel image:
+
+- Where has the loader loaded the kernel to?
+- How large is the loaded kernel?
+- Where do the text segment and the data segment end?
+- How do I get the kernel TLS image?
+
+These questions can be answered by building non-relocatable images, by writing custom linker scripts, or by having a custom loader that provides this information somehow.
+
+But there is another way!
+In fact, the main ELF linkers that I am aware of ([BFD], [gold], [LLD], [mold], and [Wild]) all have built-in ELF symbols that answer these questions when not using custom linker scripts.
+Unfortunately, many are poorly documented, so I created the [elf-symbols] crate that exposes and documents them.
+All symbols are tested on the aforementioned linkers.
+The documentation shows when each linker gained support for the respective symbol.
+
+The following symbols are straightforward:
+
+- `__executable_start` (`executable_start()`) is the start of the executable.
+- `_etext` (`text_end()`) is the end of the text segment.
+- `_edata` (`data_end()`) is the end of the data segment.
+- `_end` (`executable_end()`) is the end of the executable.
+
+`__ehdr_start` (`elf_header()`) is especially interesting.
+It allows programs to examine themselves by reading their ELF headers (file headers and program headers).
+This can be used to get TLS image information, for example.
+
+Note that these symbols are ELF specific, though, so they cannot be used when linking to something else, such as a PE32+ UEFI executable.
+
+#### Examples
 
+```rust
+println!("Executable start: {:p}", elf_symbols::executable_start());
+println!("ELF header:       {:p}", elf_symbols::elf_header());
+println!("Text segment end: {:p}", elf_symbols::text_end());
+println!("Data segment end: {:p}", elf_symbols::data_end());
+println!("Executable end:   {:p}", elf_symbols::executable_end());
+```
 
+[BFD]: https://sourceware.org/git/?p=binutils-gdb.git;a=tree;f=ld;h=b1662159cdd15bb857e04e42bd26361c0d406099;hb=5e56594815854de5eca35c7c04b11705d0f19c02
+[gold]: https://sourceware.org/git/?p=binutils-gdb.git;a=tree;f=gold;h=ac6272c7bb3ad02524b2ca86a2cf9b68e9ca30ca;hb=5e56594815854de5eca35c7c04b11705d0f19c02
+[LLD]: https://github.com/llvm/llvm-project/tree/llvmorg-22.1.8/lld
+[mold]: https://github.com/rui314/mold/tree/v2.41.0
+[Wild]: https://github.com/wild-linker/wild/tree/0.9.0
+[elf-symbols]: https://crates.io/crates/elf-symbols
 
 ## Join Us?