EFIRT(9)

✨ NAME ✨

okay bestie, welcome to efirt(9) — that's the kernel access to UEFI runtime services page, and yes it's giving very "deep magic, do not touch unless you know what you're doing" energy 💅

the whole fam is here: efirt, efi_rt_ok, efi_get_table, efi_get_time, efi_get_time_capabilities, efi_reset_system, efi_set_time, efi_var_get, efi_var_nextname, efi_var_set.

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🌸 SYNOPSIS 🌸

options EFIRT

#include <sys/efi.h>

int
efi_rt_ok(void);

int
efi_get_table(struct uuid *uuid, void **ptr);

int
efi_get_time(struct efi_tm *tm);

int
efi_get_time_capabilities(struct efi_tmcap *tmcap);

int
efi_reset_system(void);

int
efi_set_time(struct efi_tm *tm);

int
efi_var_get(uint16_t *name, struct uuid *vendor, uint32_t *attrib,
      size_t *datasize, void *data);

int
efi_var_nextname(size_t *namesize, uint16_t *name, struct uuid *vendor);

int
efi_var_set(uint16_t *name, struct uuid *vendor, uint32_t *attrib,
      size_t *datasize, void *data);

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🦋 DESCRIPTION 🦋

okay so first thing, the group-chat announcement: every single one of these calls returns ENXIO if UEFI runtime services aren't available. no services, no vibes. and also, efirt is currently only available on amd64 and arm64 — so if you're on something else, this whole page is just ✨aesthetic✨ for you.

efi_rt_ok() 💖

returns 0 if UEFI runtime services are present and functional, or ENXIO if not. that's it. that's the vibe check.

efi_get_table() 🔍

gets a table by uuid from the UEFI system table. returns 0 if the table was found, and populates *ptr with the address. returns ENXIO if the configuration table or system table are unset. returns ENOENT if the requested table cannot be found. (rip, the table ghosted you.)

efi_get_time() ⏰

gets the current time from the RTC, if it's available. returns 0 and populates the struct efi_tm on success. returns EINVAL if the struct efi_tm is NULL, or EIO if the time could not be retrieved due to a hardware error.

efi_get_time_capabilities() 🎀

gets the capabilities from the RTC. returns 0 and populates the struct efi_tmcap on success. returns EINVAL if the struct efi_tm is NULL, or EIO if the time could not be retrieved due to a hardware error.

efi_reset_system() 💀

requests a warm reset and reboot of the system. yeah. that's a whole thing. it just asks for it, no arguments, no return value to check. main character move tbh.

efi_set_time() 🕰️

sets the time on the RTC to the time described by the struct efi_tm passed in. returns 0 on success, EINVAL if a time field is out of range, or EIO if the time could not be set due to a hardware error.

efi_var_get() 🍓

fetches the variable identified by vendor and name. returns 0 and populates attrib, datasize, and data on success. otherwise, one of these little guys comes back at you:

• ENOENT — the variable was not found.
• EOVERFLOW — datasize is not sufficient to hold the variable data. namesize is updated to reflect the size needed to complete the request.
• EINVAL — one of name, vendor, or datasize are NULL. alternatively, datasize is large enough to hold the response but data is NULL.
• EIO — the variable could not be retrieved due to a hardware error.
• EDOOFUS — the variable could not be retired due to an authentication failure.

not the EDOOFUS. iconic error name, honestly. no notes. 👑

efi_var_nextname() 🌈

this one's for enumeration of variables, aka scrolling the list. on the initial call to efi_var_nextname(), name should be an empty string. subsequent calls should pass in the last name and vendor returned, until ENOENT is returned. returns 0 and populates namesize, name, and vendor with the next variable's data. otherwise, returns one of the following:

• ENOENT — the next variable was not found.
• EOVERFLOW — datasize is not sufficient to hold the variable data. namesize is updated to reflect the size needed to complete the request.
• EINVAL — one of name, vendor, or datasize are NULL.
• EIO — the variable could not be retrieved due to a hardware error.

efi_var_set() ✨

sets the variable described by name and vendor. returns 0 if the variable has been successfully. otherwise, returns one of the following:

• EINVAL — either attrib was an invalid combination of attributes, datasize exceeds the maximum allowed size, or name is an empty Unicode string.
• EAGAIN — not enough storage is available to hold the variable and its data.
• EIO — the variable could not be saved due to a hardware error.
• EROFS — the variable in question is read-only or may not be deleted.
• EDOOFUS — the variable could not be set due to an authentication failure.
• ENOENT — the variable trying to be updated or deleted was not found.

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👀 SEE ALSO 👀

• efidev(4)

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🫶 AUTHORS 🫶

this manual page was written by Kyle Evans <kevans@FreeBSD.org>. thank you Kyle, you ate 💖

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and that's the whole page bestie, no cap — this beauty came from Debian, dated August 12, 2018, and it lives in section EFIRT(9) of the Kernel Developer's Manual. go forth and talk to your firmware responsibly 🧚✨