ata_format_dsm_trim_descr(9)

📦 version 7.3.1, in nixpkgs unstable

okay bestie, this is ata_format_dsm_trim_descr(9) from the Kernel API Manual — yes, the manual name is right there, and the whole page is giving kernel-helper main character energy. let's go 💅✨

🎀 NAME 🎀

ata_format_dsm_trim_descr — SATL Write Same to DSM Trim ✨

✨ SYNOPSIS ✨

here's the signature, bestie, and yes it's exactly this:

       size_t ata_format_dsm_trim_descr (struct scsi_cmnd *cmd , size_t size ,
       u64 sector , u32 count );

🌸 ARGUMENTS 🌸

  • cmd — SCSI command being translated. it's the thing getting the translation glow-up 💖
  • size — DSM TRIM payload size in bytes (a multiple of 512). literally a multiple of 512, okay? ✨
  • sector — Starting sector. the starting point of the whole saga 🎬
  • count — Total Range of request in logical sectors. capital R, official business 👑

🦋 DESCRIPTION 🦋

Okay so the job is: rewrite the WRITE SAME descriptor to be a DSM TRIM little-endian formatted descriptor. it's giving "same descriptor, new format" and honestly? slay 💅

The payload is a list of size / 8 entries of the format: 63:48 Range Length 47:0 LBA.

Range Length of 0 is ignored. LBA's should be sorted order and not overlap — no messy overlapping LBAs, bestie, that's not the vibe 🚫

💀 NOTE 💀

this is the same format as ADD LBA(S) TO NV CACHE PINNED SET. iykyk ✨

The descriptor is written straight into the WRITE SAME data-out buffer; ata_dsm_trim_pages guarantees size does not exceed that buffer (one logical block). An atomic sg_miter mapping is used so this works from the command submission path and, unlike page_address, copes with a high memory payload. that's the little technical moment and it ate 🔥

🫶 RETURN 🫶

Number of bytes written into the data-out buffer. that's the return, periodt 💖

🌈 SEE ALSO 🌈

Kernel file ./drivers/ata/libata-scsi.c, plus the whole group chat:

xoxo, your kernel bestie 💖 — from ./drivers/ata, October 2026, ata_format_dsm_trim_descr(9), byeeeeee 🎀

📦 where this page comes from