{"action":"created","issue":{"url":"https://api.github.com/repos/pbatard/efifs/issues/3","repository_url":"https://api.github.com/repos/pbatard/efifs","labels_url":"https://api.github.com/repos/pbatard/efifs/issues/3/labels{/name}","comments_url":"https://api.github.com/repos/pbatard/efifs/issues/3/comments","events_url":"https://api.github.com/repos/pbatard/efifs/issues/3/events","html_url":"https://github.com/pbatard/efifs/issues/3","id":179755691,"number":3,"title":"EFI boot entries for integrated custom filesystem modules","user":{"login":"janos666","id":7944953,"avatar_url":"https://avatars.githubusercontent.com/u/7944953?v=3","gravatar_id":"","url":"https://api.github.com/users/janos666","html_url":"https://github.com/janos666","followers_url":"https://api.github.com/users/janos666/followers","following_url":"https://api.github.com/users/janos666/following{/other_user}","gists_url":"https://api.github.com/users/janos666/gists{/gist_id}","starred_url":"https://api.github.com/users/janos666/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/janos666/subscriptions","organizations_url":"https://api.github.com/users/janos666/orgs","repos_url":"https://api.github.com/users/janos666/repos","events_url":"https://api.github.com/users/janos666/events{/privacy}","received_events_url":"https://api.github.com/users/janos666/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":2,"created_at":"2016-09-28T12:13:50Z","updated_at":"2016-09-28T23:18:41Z","closed_at":null,"body":"I want to try and use the btrfs efi module (replacing the factory fat module with this custom btrfs module in a psychical motherboard's firmware) to boot an efistub linux kernel from a \"whole-disk\" type btrfs (no partitions but \"mkfs.btrfs /dev/sda\").\r\n\r\nIs it even possible if the system root is a non-default subvolume? Does this module automatically load all sub-volumes as directories?\r\n\r\nCan I use efibootmgr to create an efi boot entry for this?\r\nThe only problem I see is efibootmgr assuming a partition (preferably an EFI System type partition, I guess) rather than a disk (there is a --part option but I think it defaults to 1, thus excluding it doesn't mean it points to the disk instead of a partition).\r\n\r\nA slight extra: it would be a RAID-1 profile btrfs but it should not matter as long as it's a true read-only mount...\r\n\r\nThis way everything could be kept on check-summed and redundant storage while getting rid of all the \"legacy\" tools such as disk partitions, bios boot loaders, and old filesystems (FAT)."},"comment":{"url":"https://api.github.com/repos/pbatard/efifs/issues/comments/250329403","html_url":"https://github.com/pbatard/efifs/issues/3#issuecomment-250329403","issue_url":"https://api.github.com/repos/pbatard/efifs/issues/3","id":250329403,"user":{"login":"janos666","id":7944953,"avatar_url":"https://avatars.githubusercontent.com/u/7944953?v=3","gravatar_id":"","url":"https://api.github.com/users/janos666","html_url":"https://github.com/janos666","followers_url":"https://api.github.com/users/janos666/followers","following_url":"https://api.github.com/users/janos666/following{/other_user}","gists_url":"https://api.github.com/users/janos666/gists{/gist_id}","starred_url":"https://api.github.com/users/janos666/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/janos666/subscriptions","organizations_url":"https://api.github.com/users/janos666/orgs","repos_url":"https://api.github.com/users/janos666/repos","events_url":"https://api.github.com/users/janos666/events{/privacy}","received_events_url":"https://api.github.com/users/janos666/received_events","type":"User","site_admin":false},"created_at":"2016-09-28T23:18:40Z","updated_at":"2016-09-28T23:18:40Z","body":"Thanks you for the answers.\r\n\r\n@pbatard \r\n\r\nSorry for using this issue tracker for this topic but it seemed to be the best place.\r\n\r\nMaking it clear how these drivers work essentially the same way as Grub answered some possible questions.\r\n\r\nI thought efibootmgr might be of general interest because I assumed the main purpose of these drivers was to make booting from these filesystems possible.\r\n\r\n\r\n@Ferroin\r\n\r\nHaving two RAID-1 Btrfs filesystems (one on an ESP and one on the rest of the disks as a second partition) sound like a nice compromise. (I keep forgetting GPT itself is duplicated on the disk and it's also check-summed, thus protected against random sector-level corruption, so it's not a liability like MBR.)\r\n\r\nI always disliked partitions in general. I always seek a way to avoid them or prefer to use the absolute minimal number of them (might as well just a single one per disk). I think it's silly to chop the space up into discrete, static sized slices, unless it's explicitly desired for some good reason (much better reason than \"just because\" or \"we always do that\"). (The worst part is when you realize you could not predict the future [duh...] and you want to manipulate [resize/rearrange/etc] those partitions while keeping all the data in all the filesystems intact. -> Well, don't forget to cross your fingers and pray...!)\r\n\r\nSurprise: I never really liked bootloaders either. :)\r\nSometimes they can help you recovering from small errors fasts and easily (like a kernel upgrade which didn't go as planned). But they are also a liability. For example, you can just as easily break the functionality of the bootloader during a system upgrade or configuration change as you would with the kernel (even is it's less likely in usual practice due to some other, likely factors) but you have one more thing to keep in mind and worry about. And they usually reside in disk space as \"raw\" (leftover gaps along partitions, in boot partitions withouth filesystems, or may be in \"dumb\" filesystems like FAT, so... it's usually far from ideal). Of course, the motherboard firmware can also break (or the whole hardware can burn down, etc) but still one less thing to worry about when you make changes or try to debug a problem if you don't have bootloader on disk(s).\r\n\r\nHaving that said about partitions, an ESP with Btrfs housing the bootloader/efistubkernel sounds better than putting it into \"raw\" space or into a FAT filesystem. That makes everything pretty solid in theory (including the configuration of the firmware boot option if you can give it a partition). The only \"unstable magic\" lays in the firmware modification (I plan to upgrade the motherboard soon, so I have no idea if the new one might cooperate and load modified code or not)."}}
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