On Wed, Dec 16, 2020 at 2:28 PM Chris Murphy <lists@xxxxxxxxxxxxxxxxx> wrote: > > On Tue, Dec 15, 2020 at 12:14 PM Brian C. Lane <bcl@xxxxxxxxxx> wrote: > > > > On Mon, Dec 14, 2020 at 11:03:03PM -0700, Chris Murphy wrote: > > > Right. The two I've previously suggested: btrfs seed and dm-verity. > > > Every read is verified, the user can't opt out, and they are more > > > performant than checkisomd5. Upon detecting error, both emit EIO which > > > is handled at the application level, i.e. stop the installation and > > > notify the user. > > > > Those would require significant changes to how live works though. Simple > > is better. > > I agree simpler is better. Btrfs is a drop-in replacement for ext4, > assuming no other changes. Like I said, Will Woods had this working a > long time ago. This is not my original idea. I've tried it and it > works fine, and we get integrity checking for data and metadata for > free.[1] I'm not sure what significant change you think is required. > https://www.redhat.com/archives/anaconda-devel-list/2011-March/msg00263.html I don't know where the implied changes below would happen, or even if they'd be accepted. But I did successfully create two Btrfs based images that require no other change to bits in the image itself (same initramfs, kernel, identical files in the Fedora created ISO, etc). I tested with and without the seed feature flag enabled. Everything is assembled correctly, and works as expected. Optical, USB stick media, UEFI and BIOS. A. btrfs+squashfs All I did here was create a new btrfs rootfs, copied the ext4 rootfs from a rawhide image, then mksquashfs to nest it. Then xorriso to make an ISO. No change to boot parameters. I guess it's lorax, pungi, koji that would need a switch to make such a thing, and do mkfs.btrfs instead of mkfs.ext4. B. plain btrfs In this case I used native btrfs compression, zstd-force:11, and then skipped mksquashfs. I also added rd.live.overlay.overlayfs when booting the ISO. This is a variation on the plain squashfs option. I guess new code to skip the mksquashfs step could be significant, I'm not sure. The difficulty with this ISO image, no matter the file system, is that it's an ISO 9660 image first and foremost. And thus read-only. I'll followup on this aspect of my findings in the "Pre-made live image with actual functioning persistent storage?" thread. -- Chris Murphy _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx
