Hello everyone, MTD devices were historically partitioned using fixed partitions schemes defined in the kernel device tree or on the cmdline. More recently, a bunch of dynamic parsers have been introduced, allowing partitioning information to be stored in-band. However, unlike disks, parsers for MTD devices do not support runtime discovery of the partition format. This format is instead named in the device-tree using a compatible string. The GUID Partition Table is one of the most common ways of partitioning a block device. As of now, there is no support in the MTD layer for parsing GPT tables. Indeed, use cases for layouts like GPT on raw Flash devices are rare, and for good reason since these partitioning schemes are sensitive to bad blocks in strategic locations such as LBA 2. Moreover, they do not allow proper wear-leveling to be performed on the full span of the device. However, allowing GPT to be used on MTD devices can be practical in some cases. In the context of an A/B OTA upgrade that can act on either NOR of eMMC devices, having the same partition table format for both kinds of devices can simplify the task of the update software. This series adds a fully working MTD GPT parser to the kernel. Use of the parser is restricted to NOR flash devices, since NAND flashes are too susceptible to bad blocks. To ensure coherence and code-reuse between subsystems, I've factored device-agnostic code from the block layer GPT parser and moved it to a new generic library in lib/gpt.c. No functional change is intended in the block layer parser. I understand that this can seem like a strange feature for MTD devices, but with the restriction to NOR devices, the partition table can be fairly reliable. Moreover, this addition fits nicely into the MTD parser model. Please tell me what you think. Best Regards, Romain Romain Gantois (6): block: partitions: efi: Move efi.h header to include/linux/gpt.h block: partitions: efi: Fix some style issues block: partitions: efi: Separate out GPT-specific code block: partitions: efi: Move GPT-specific code to a new library drivers: mtd: introduce GPT parser for NOR flash devices dt-bindings: mtd: add GPT partition bindings .../bindings/mtd/partitions/gpt.yaml | 41 ++ .../bindings/mtd/partitions/partitions.yaml | 1 + MAINTAINERS | 4 +- block/partitions/Kconfig | 2 +- block/partitions/efi.c | 478 +++--------------- block/partitions/msdos.c | 2 +- drivers/mtd/parsers/Kconfig | 10 + drivers/mtd/parsers/Makefile | 1 + drivers/mtd/parsers/gpt.c | 222 ++++++++ include/linux/efi.h | 18 + block/partitions/efi.h => include/linux/gpt.h | 72 ++- lib/Kconfig | 3 + lib/Makefile | 3 + lib/gpt.c | 342 +++++++++++++ 14 files changed, 777 insertions(+), 422 deletions(-) create mode 100644 Documentation/devicetree/bindings/mtd/partitions/gpt.yaml create mode 100644 drivers/mtd/parsers/gpt.c rename block/partitions/efi.h => include/linux/gpt.h (61%) create mode 100644 lib/gpt.c -- 2.43.0
