| Message ID | 20200515014143.12984-5-digetx@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Introduce NVIDIA Tegra Partition Table | expand |
On Fri, May 15, 2020 at 04:41:41AM +0300, Dmitry Osipenko wrote: >Most of consumer-grade NVIDIA Tegra devices use a proprietary bootloader >that can't be easily replaced because it's locked down using Secure Boot >cryptography singing and the crypto keys aren't given to a device owner. ^^^^^^^ typo >These devices usually have eMMC storage that is partitioned using a custom >NVIDIA Tegra partition table format. Of course bootloader and other >"special things" are stored on the eMMC storage, and thus, the partition >format can't be changed. ...
15.05.2020 13:03, Steve McIntyre пишет: > On Fri, May 15, 2020 at 04:41:41AM +0300, Dmitry Osipenko wrote: >> Most of consumer-grade NVIDIA Tegra devices use a proprietary bootloader >> that can't be easily replaced because it's locked down using Secure Boot >> cryptography singing and the crypto keys aren't given to a device owner. > ^^^^^^^ typo >> These devices usually have eMMC storage that is partitioned using a custom >> NVIDIA Tegra partition table format. Of course bootloader and other >> "special things" are stored on the eMMC storage, and thus, the partition >> format can't be changed. > > ... > Thanks! I'll correct it in v5.
diff --git a/block/partitions/efi.c b/block/partitions/efi.c index b64bfdd4326c..48e4c2aeeded 100644 --- a/block/partitions/efi.c +++ b/block/partitions/efi.c @@ -103,6 +103,12 @@ force_gpt_fn(char *str) } __setup("gpt", force_gpt_fn); +/* Used by NVIDIA Tegra partition parser in order to convey a non-standard + * location of the GPT entry for lookup. This variable should be set before + * efi_partition() invocation for instructing parser to look up GPT entry at + * the given sector, and it should be unset after completion of the invocation. + */ +sector_t force_gpt_sector; /** * efi_crc32() - EFI version of crc32 function @@ -621,6 +627,10 @@ static int find_valid_gpt(struct parsed_partitions *state, gpt_header **gpt, if (!good_agpt && force_gpt) good_agpt = is_gpt_valid(state, lastlba, &agpt, &aptes); + if (!good_agpt && force_gpt && force_gpt_sector) + good_agpt = is_gpt_valid(state, force_gpt_sector, + &agpt, &aptes); + /* The obviously unsuccessful case */ if (!good_pgpt && !good_agpt) goto fail; diff --git a/block/partitions/efi.h b/block/partitions/efi.h index 8cc2b88d0aa8..630cf21439af 100644 --- a/block/partitions/efi.h +++ b/block/partitions/efi.h @@ -113,4 +113,6 @@ typedef struct _legacy_mbr { __le16 signature; } __packed legacy_mbr; +extern sector_t force_gpt_sector; + #endif
Most of consumer-grade NVIDIA Tegra devices use a proprietary bootloader that can't be easily replaced because it's locked down using Secure Boot cryptography singing and the crypto keys aren't given to a device owner. These devices usually have eMMC storage that is partitioned using a custom NVIDIA Tegra partition table format. Of course bootloader and other "special things" are stored on the eMMC storage, and thus, the partition format can't be changed. The Tegra partition format has been reverse-engineered, but NVIDIA did another odd thing by merging "boot" and "main" eMMC HW partitions into a single virtual partition in theirs bootloader. This is not supported by Linux kernel and can't be easily implemented. Hence partition table entry isn't accessible by kernel if it's located at the "boot" eMMC partition. Luckily this is a rare case in practice and even if it's the case, likely that the proprietary bootloader will supply kernel with a non-standard gpt_sector= cmdline option. This gpt_sector= argument points at a GPT entry that is placed at a non-standard location on the eMMC storage. This patch allows to support the non-standard cmdline option for NVIDIA Tegra devices without bothering any other platforms. The force_gpt_sector variable should be set before invoking efi_partition() and be unset after the invocation completion. This variable, if set, instructs GPT parser to look up GPT entry at the given sector in addition to the standard GPT locations. This patch is based on the original work done by Colin Cross for the downstream Android kernel. Signed-off-by: Dmitry Osipenko <digetx@gmail.com> --- block/partitions/efi.c | 10 ++++++++++ block/partitions/efi.h | 2 ++ 2 files changed, 12 insertions(+)