qcom_mdt_read_metadata(9)

📦 version 7.3.1, in nixpkgs unstable

💅 qcom_mdt_read_metadata(9) — the kernel API manual, but make it make sense

okay so bestie, welcome to the qcom_mdt_read_metadata page from the Kernel API Manual ✨ this one is literally about pulling a header + metadata blob out of an mdt or an mbn file, and ngl it's giving "small function, big job" energy 🎀

🌸 NAME 🌸

qcom_mdt_read_metadata — read header and metadata from mdt or mbn

like, that's it, that's the whole vibe. header + metadata, out of mdt or mbn, no cap 💅

✨ SYNOPSIS ✨

void * qcom_mdt_read_metadata (const struct firmware *fw , size_t
*data_len , const char *fw_name , struct device *dev );

she returns a void *, she takes four things, and yes you have to keep them in that exact order 🫶

🦋 ARGUMENTS 🦋

  • fw — the firmware of the mdt header or the mbn. this is the source material, the main character of the whole operation 👑
  • data_len — length of the read metadata blob. she's a pointer, so the function can hand you back how big the thing actually is 📏
  • fw_name — name of the firmware, and it's used for construction of segment file names. so yes, she's functional, not just decorative 🎀
  • dev — device handle to associate resources with. gotta know which device these resources belong to, periodt 🔥

💜 DESCRIPTION 💜

okay so here's the situation, and it's honestly kind of iconic 😭 The mechanism that performs the authentication of the loading firmware expects an ELF header directly followed by the segment of hashes — with no padding inbetween. like, none. zero. touching. that's the whole rule.

So this function allocates a chunk of memory for this pair (the header + the hashes, they're a package deal 💖) and copies the two pieces into the buffer.

And here's the little plot twist for split firmware 🌈 — in that case, the hash is found directly following the ELF header, rather than at p_offset as described by the second program header. yes, different location. yes, it matters. iykyk.

⚠️ bestie, listen to me: the caller is responsible to free (kfree) the returned pointer. she gives you memory, you give it back. that's the deal. don't leave her hanging 🙈

⭐ RETURN ⭐

pointer to data, or ERR_PTR 🫡 so like — check that thing before you go dereferencing it, fr fr.

👑 SEE ALSO 👑

Kernel file ./drivers/soc/qcom/mdt_loader.c, plus these lovely little siblings:

go read them, they're all part of the same friend group 💅✨

and that's the page!! 🦋 this little gem lives under ./drivers/soc/qcom and it's dated October 2026, so like — mark your calendar, screenshot it, put it on your fyp, whatever you gotta do. bye bestie, go free that pointer 💖🌸🎀

📦 where this page comes from