{"id":334,"date":"2019-09-24T09:18:12","date_gmt":"2019-09-24T09:18:12","guid":{"rendered":"https:\/\/immerhax.com\/?p=334"},"modified":"2019-09-24T09:18:12","modified_gmt":"2019-09-24T09:18:12","slug":"linux-empty-sys-firmware-efi-efivars","status":"publish","type":"post","link":"https:\/\/immerhax.com\/?p=334","title":{"rendered":"Linux: Empty \/sys\/firmware\/efi\/efivars"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">When applying the preempt_rt patch to the Linux kernel, EFI variables at runtime are disabled by default, seemingly due to high latencies (<a href=\"https:\/\/www.spinics.net\/lists\/linux-rt-users\/msg19980.html\">https:\/\/www.spinics.net\/lists\/linux-rt-users\/msg19980.html<\/a>). If you still need EFI variables accessible for userspace applications like efibootmgr, add &#8220;efi=runtime&#8221; to the kernel parameters\/arguments. This will re-enable the possibility to mount efivarfs with &#8220;mount -t efivarfs none \/sys\/firmware\/efi\/efivars&#8221;. This will of course not magically make the above mentioned latencies disappear, so use this at your own discretion.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>When applying the preempt_rt patch to the Linux kernel, EFI variables at runtime are disabled by default, seemingly due to high latencies (https:\/\/www.spinics.net\/lists\/linux-rt-users\/msg19980.html). If you still need EFI variables accessible for userspace applications like efibootmgr, add &#8220;efi=runtime&#8221; to the kernel parameters\/arguments. This will re-enable the possibility to mount efivarfs with &#8220;mount -t efivarfs none \/sys\/firmware\/efi\/efivars&#8221;. &hellip; <a href=\"https:\/\/immerhax.com\/?p=334\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">Linux: Empty \/sys\/firmware\/efi\/efivars<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-334","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/immerhax.com\/index.php?rest_route=\/wp\/v2\/posts\/334","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/immerhax.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/immerhax.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/immerhax.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/immerhax.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=334"}],"version-history":[{"count":1,"href":"https:\/\/immerhax.com\/index.php?rest_route=\/wp\/v2\/posts\/334\/revisions"}],"predecessor-version":[{"id":335,"href":"https:\/\/immerhax.com\/index.php?rest_route=\/wp\/v2\/posts\/334\/revisions\/335"}],"wp:attachment":[{"href":"https:\/\/immerhax.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=334"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/immerhax.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=334"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/immerhax.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=334"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}