plpks_read_os_var(9)

🦋 NAME 🦋

okay so this is plpks_read_os_var — the little function that fetches the data for the specified variable that is owned by the OS consumer. that's it, that's the whole vibe 💅

this page lives in the Kernel API Manual, btw, in case you were wondering where we're at 🎀

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✨ SYNOPSIS ✨

int plpks_read_os_var (struct plpks_var *var );

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🫶 ARGUMENTS 🫶

• var — the variable to be read from the PLPKS. that's the one, bestie, that's who we're reading 💖

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💀 DESCRIPTION 💀

so like, lowkey the whole deal here is that the consumer or the owner of the object is the os kernel. main character energy, honestly 👑

the H_PKS_READ_OBJECT HCALL is the thing that actually reads an object from the PLPKS. iconic.

now listen up because this part matters 🔥 — the caller must allocate the buffer var->data and specify the length for this buffer in var->datalen. that's on you, not on the function. no cap.

but hmm, what if you don't have a buffer yet? 🧚 then it's fine, because if no buffer is provided, var->datalen will be populated with the requested object's size. so you can literally ask "how big is this thing" first and then come back with the right-sized buffer. we love a two-step moment 💅

😭 possible reasons for the returned errno values

• -ENXIO — if PLPKS is not supported 🙈
• -EIO — if PLPKS access is blocked due to the LPAR's state; if an error occurred while processing the request 😵‍💫
• -EINVAL — if invalid authorization parameter; if invalid object label parameter; if invalid object label len parameter; if invalid output data parameter; if invalid output data len parameter 🚩
• -EPERM — if access is denied 🙅‍♀️
• -ENOENT — if the requested object was not found 🕵️‍♀️
• -EFBIG — if the requested object couldn't be stored in the buffer provided 😤 (buffer too smol, tragic)
• -EBUSY — if unable to handle the request 💀

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🌈 RETURN 🌈

on success, 0 is returned. if not? a negative errno. simple as that, bestie ✨

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🍓 SEE ALSO 🍓

the kernel file, right here:

./arch/powerpc/platforms/pseries/plpks.c

and the whole PLPKS friend group, obviously 👑:

plpks_get_version(9), plpks_get_objoverhead(9), plpks_get_maxpwsize(9), plpks_get_maxobjectsize(9), plpks_get_maxobjectlabelsize(9), plpks_get_totalsize(9), plpks_get_usedspace(9), plpks_get_supportedpolicies(9), plpks_get_maxlargeobjectsize(9), plpks_get_signedupdatealgorithms(9), plpks_get_wrappingfeatures(9), plpks_get_passwordlen(9), plpks_is_available(9), plpks_signed_update_var(9), plpks_write_var(9), plpks_remove_var(9), plpks_wrapping_is_supported(9), plpks_gen_wrapping_key(9), plpks_wrap_object(9), plpks_unwrap_object(9), plpks_read_fw_var(9), plpks_read_bootloader_var(9), plpks_populate_fdt(9), plpks_early_init_devtree(9)

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and that's the page, bestie 🫶 this little gem comes from ./arch/powerpc/platforms/pseries, dated October 2026, and it's plpks_read_os_var(9) — go read some OS-owned variables, you got this 💜✨