Date: Mon, 09 Feb 2026 05:39:18 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 293054] Document the FreeBSD BootEnv and NextBootEnv EFI variables Message-ID: <bug-293054-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=293054 Bug ID: 293054 Summary: Document the FreeBSD BootEnv and NextBootEnv EFI variables Product: Documentation Version: Latest Hardware: Any OS: Any Status: New Severity: Affects Some People Priority: --- Component: Manual Pages Assignee: bugs@FreeBSD.org Reporter: bblake@techie.com CC: doc@FreeBSD.org In loader.efi(8), there is a section, "Additional Environment Variables". It currently reads: loader.efi loads some extra variables early in startup from /efi/freebsd/loader.env from the EFI partition. Only simple variables can be set here. It can be useful to specify the root filesystem: rootdev=disk0s1a What it doesn't say is that that pathname is a default that can be changed. Specifically, the FreeBSD EFI variable LoaderEnv sets that pathname, which defaults to /efi/freebsd/loader.env if the variable does not exist. Also, NextLoaderEnv can be set to a pathname and that variable is then deleted after it is used. My suggested documentation change is: ======== loader.efi can set variables early in startup from a file on the EFI partition. By default, that file is /efi/freebsd/loader.env. It can be changed by setting the FreeBSD EFI variable LoaderEnv, as in: echo -n /efi/freebsd/alt.env | efivar -w -t 7 -n cfee69ad-a0de-47a9-93a8-f63106f8ae99-LoaderEnv After that is executed, the file /efi/freebsd/alt.env is used instead of /efi/freebsd/loader.env. See efivar(8) for more information on setting EFI variables. In addition, the EFI variable NextLoaderEnv can be set to the pathname of a second startup file. That variable is deleted immediately after its value is retrieved, so setting it will affect only the next boot attempt. For either variable, a missing file is silently ignored. A typical use for the startup file is to change the boot partition. To do that, you can put something like rootdev=disk0p15 into the file. The set of useful variables is small, as most will be changed later. In addition, setting those variables that are supposed to cause side effects when set does not work and may cause breakage; don't do that. The startup file contains a series of assignments separated by spaces, tabs, or newlines. Quotes are not given any special treatment. If no =value is given, the value 1 is used. Invalid syntax and the like are silently ignored. ======== loader.efi uses code from sys/kern/subr_boot.c to parse the files and that code parses boot flags as well. But the "howto" variable is discarded, making that useless. However, -S<text> is handled exactly as if comconsole_speed=<text> had been entered, setting the variable. That's probably unintentional since none of the other boot flags can be set from the files, so this probably shouldn't be documented. Still, if one wanted to be completist, an additional paragraph could be added to the description. -- You are receiving this mail because: You are the assignee for the bug.home | help
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