On Mon, Oct 20, 2025 at 11:04 AM Daniel Kiper <[email protected]> wrote: > > On Fri, Oct 17, 2025 at 05:01:31PM +0800, Michael Chang via Grub-devel wrote: > > This patch series adds support for storing the GRUB environment block in > > a reserved area of the Btrfs header. On copy on write filesystems such > > as Btrfs, the normal file based envblk cannot be updated safely at > > runtime because block addresses are not stable. The reserved area > > provides a fixed location that GRUB can write directly, allowing > > commands such as grub-reboot and savedefault to work on Btrfs volumes. > > > > The series proceeds in small chunks to keep each change buildable and > > easier to review. The first patches add new data structures and helpers > > for creating, opening, and writing an environment block in the reserved > > area. Later patches update set_variables, unset_variables, and > > list_variables so they can use the external block when it is present. An > > entry is added to the Btrfs header to reserve space at 256 KiB for the > > environment block. Finally, grub.cfg is modified so that load_env and > > save_env use the external block automatically when env_block is defined. > > > > The first two patches are new in this series as feedback from the review > > to use a portable string specifier for size_t. Unfortunately the z > > length modifier is missing in GRUB printf routine's format specifier. > > The new patches add support and test case for that. In theory they can > > be reviewed separately. > > > > And also yet another new patch "btrfs: update doc link for bootloader > > support" added at the end to address v3 review feedback. > > > > v2: > > - Define ENV_BTRFS_OFFSET as 256*1024 > > - Do not conflate type and variable definitions > > - Align typedef with struct declaration to follow coding style > > - Use bool as the return type of is_abstraction() > > - Add "if (dev->disk != NULL)" check in is_abstraction() > > - Refine the loop logic in is_abstraction() tests > > - Remove extra indentation and redundant lines in read_envblk_fs > > - Use off_t and size_t for offset and size variables, fix similar cases > > throughout > > - Use explicit check "(fp == NULL)" instead of "(! fp)", fix similar > > cases throughout > > - Use bool for the "found" field in var_lookup_ctx > > - Add documentation describing the Btrfs environment block and special > > environment block variables > > v3: > > - Replace !fp with explicit (fp == NULL) for clarity > > - Fix missing blank line before return statement > > - Fix missing space after cast operator > > v4: > > - Rename ENV_BTRFS_OFFSET to GRUB_ENV_BTRFS_OFFSET > > - Move GRUB_ENV_BTRFS_OFFSET into "btrfs: add environment block to > > reserved header area" > > - Adjust patch order to resolve relocated GRUB_ENV_BTRFS_OFFSET > > - Add patch "btrfs: update doc link for bootloader support" > > - Do better typedef > > - Add heads-up comments to both fs_envblk_spec and btrfs_head that they > > have to stay in sync > > - Fix a few places to use explicit checks for NULL, true/false etc > > - Use goto labels to cleanup consistently > > - Mark function names with trailing "()" in commits and comments > > - Rename envblk_fs to envblk_on_block for better clarity > > - Avoid redundant curly braces in if .. else if clause > > - Highlight overflow guard around envioronment block in embed_region > > - Rename a few functions for clarity > > - Use portable printf formats for off_t and size_t > > - Support z length modifier in GRUB printf format string > > - Add z modifier to printf unit test > > v5: > > - Move fs_envblk_spec table into "btrfs: add environment block to > > reserved header area" > > - Move "util/grub-editenv: add basic structures and probe call for > > external envblk" the 9th patch behind all wiring patches and rename it > > to "util/grub-editenv: add probe call for external envblk" as it now > > only does probing > > - Add fs_envblk_init() to wire open helper in the base structures into > > patch "util/grub-editenv: add fs_envblk open helper" > > - Add "Man 5 btrfs" an alternate to the doc link > > v6: > > - Move fs_envblk_spec structure typedef and variable from "btrfs: add > > environment block to reserved header area" into "util/grub-editenv: > > add fs_envblk open helper". The fs_envblk_spec remains empty since no > > Btrfs area is defined yet. > > - Reorder "btrfs: add environment block to reserved header area" to > > follow all groundwork patches, and provide the defined reserved area > > to fs_envblk_spec so that it becomes supported in grub-editenv. > > > > Michael Chang (12): > > misc: add z length modifier support > > tests: add z modifier printf tests > > util/grub-editenv: add fs_envblk open helper > > util/grub-editenv: add fs_envblk write helper > > util/grub-editenv: wire set_variables to optional fs_envblk > > util/grub-editenv: wire unset_variables to optional fs_envblk > > util/grub-editenv: wire list_variables to optional fs_envblk > > util/grub-editenv: add probe call for external envblk > > btrfs: add environment block to reserved header area > > 00_header.in: wire grub.cfg to use env_block when present > > docs: add Btrfs env block and special env vars > > btrfs: update doc link for bootloader support > > For all patches Reviewed-by: Daniel Kiper <[email protected]>... >
So can this land in time for GRUB 2.14? -- 真実はいつも一つ！/ Always, there's only one truth! _______________________________________________ Grub-devel mailing list [email protected] https://lists.gnu.org/mailman/listinfo/grub-devel
