iosys_map_wr_field(9)

📦 version 7.3.1, in nixpkgs unstable

💫 iosys_map_wr_field(9) 💫

okay so bestie, welcome to the Kernel API Manual — this little cutie lives in section 9 of the kernel man pages, and today we're talking about iosys_map_wr_field. it's giving "write one field, but make it architecture-aware" and honestly? iconic. 🎀

🌸 NAME 🌸

iosys_map_wr_field — write to a member of a struct in the iosys_map 💅

✨ SYNOPSIS ✨

iosys_map_wr_field (map__ , struct_offset__ , struct_type__ , field__ ,
val__ );

🦋 ARGUMENTS 🦋

  • map__ — the iosys_map structure itself. the main character, the map we're messing with 💖
  • struct_offset__ — offset from the beginning of the map, like, where the struct is actually located. yes you have to tell it 🙈
  • struct_type__ — the struct that describes the layout of the mapping. it's the blueprint, the vibe reference 🧚
  • field__ — member of the struct to read 👀 (that's what the page says, bestie, I'm just relaying it)
  • val__ — the value to write. the payload. the moment. ⭐

🔥 DESCRIPTION 🔥

so the whole point: this writes a value into the iosys_map, and it figures everything out by treating the layout as being described by a C struct that starts at struct_offset__. it calculates the field offset and size, then writes val__ in there. slay. 💅

⚠️ but listen — if that field access would end up being an un-aligned access, then you either gotta use iosys_map_memcpy_to, or your architecture has to actually support unaligned access. no cap, don't skip this part. 😭

for expected usage and memory layout, go check out iosys_map_rd_field — that's the reference, fr fr. 🫶

👑 SEE ALSO 👑

and that's the whole page, bestie! 🌈 this one came from ./include/linux, dated October 2026, and it's filed under iosys_map_wr_field(9). go write some fields, but like... aligned ones. mwah 💋✨

📦 where this page comes from