Add Add CONFIG_MTD_PARTITIONED_MASTER kernel config for aspeed arm64

[prajjwal-arista]

Description

Add CONFIG_MTD_PARTITIONED_MASTER=y to kernel config for arm64 aspeed config.

Why I did it

CONFIG_MTD_PARTITIONED_MASTER=y enables to retain the master (entire, unpartitioned) Memory Technology Device (MTD) node in user space even when the flash memory is divided into smaller partitions.
Therefore, this enables full device access which will be useful for low-level utilities, firmware backups, or flashing tools

How I did it

Added CONFIG_MTD_PARTITIONED_MASTER=y to file config.local/arm64/config.sonic-aspeed

How I tested it

Manual testing -

without the fix:

admin@sonic:~$ cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00400000 00010000 "u-boot"
mtd1: 00020000 00010000 "u-boot-env"
mtd2: 00900000 00010000 "kernel"
mtd3: 052e0000 00010000 "rofs"
mtd4: 02000000 00010000 "rwfs"
mtd5: 08000000 00010000 "bmc-secondary"

with the fix:

admin@sonic:~$ cat /proc/mtd
dev:    size   erasesize  name
mtd0: 08000000 00010000 "bmc-primary"
mtd1: 00400000 00010000 "u-boot"
mtd2: 00020000 00010000 "u-boot-env"
mtd3: 00900000 00010000 "kernel"
mtd4: 052e0000 00010000 "rofs"
mtd5: 02000000 00010000 "rwfs"
mtd6: 08000000 00010000 "bmc-secondary"

Backport

Backport required in 202608

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[mssonicbld]

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[vivekverma-arista]

cc @chander-nexthop @yxieca @saiarcot895 @nats-nokia for review

[paulmenzel]

Thank you for your patch. It’d be great if you amended the commit message:

CONFIG_MTD_PARTITIONED_MASTER=y enables to retain the master (entire, unpartitioned)
Memory Technology Device (MTD) node in user space even when the flash memory is
divided into smaller partitions.
Therefore, this enables full device access which will be useful for low-level utilities,
firmware backups, or flashing tools

Please add a section how to verify, that everything works as expected. New Linux log messages? New devices in /dev/? Please also name the device you tested this on.

[mssonicbld]

/azp run

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[prajjwal-arista]

@paulmenzel
Thanks. Updated the commit msg.

[nats-nokia]

This requires changes on our platform code.
We will adapt our code to have this kernel config change.

[saiarcot895]

@DannyIsa @chander-nexthop can you review these changes? This may require changes to your platform code as there will be an additional mtd device visible, and blind usage of that device will cause issues.

@prajjwal-arista is there any metadata on that mtd0 device to make it apparent that that is a full device and not a partition? Something in udevadm info /dev/mtd0, or similar?

[chander-nexthop]

Thanks @saiarcot895. Checked the Nexthop B27 (Aspeed) paths — no Nexthop impact. Our U-Boot env access is name-based (sonic-fw-env-config.sh greps /proc/mtd for the "u-boot-env" label), so it follows the partition after the master shows up at mtd0.

@prajjwal-arista one cleanup request: in sonic-buildimage, platform/aspeed/platform_arm64.conf hardcodes FW_ENV_DEFAULT='/dev/mtd1 ...', which now points at u-boot instead of u-boot-env after this shift. It's a different repo, but please make that change alongside this PR so the index shift is handled in one place.

[prajjwal-arista]

@saiarcot895

Here is the difference between the master device (mtd0) and a partition (mtd1) visible via udevadm info:

admin@sonic:~$ udevadm info /dev/mtd0 --no-pager
P: /devices/platform/soc@14000000/14000000.spi/spi_master/spi0/spi0.0/mtd/mtd0
M: mtd0
R: 0
J: c90:0
U: mtd
T: mtd
D: c 90:0
N: mtd0
L: 0
S: mtd/by-name/bmc-primary
E: DEVPATH=/devices/platform/soc@14000000/14000000.spi/spi_master/spi0/spi0.0/mtd/mtd0
E: DEVNAME=/dev/mtd0
E: DEVTYPE=mtd
E: OF_NAME=flash
E: OF_FULLNAME=/soc@14000000/spi@14000000/flash@0
E: OF_COMPATIBLE_0=jedec,spi-nor
E: OF_COMPATIBLE_N=1
E: MAJOR=90
E: MINOR=0
E: SUBSYSTEM=mtd
E: USEC_INITIALIZED=17151283
E: NVME_HOST_IFACE=none
E: DEVLINKS=/dev/mtd/by-name/bmc-primary
E: TAGS=:systemd:
E: CURRENT_TAGS=:systemd:

admin@sonic:~$ udevadm info /dev/mtd1 --no-pager
P: /devices/platform/soc@14000000/14000000.spi/spi_master/spi0/spi0.0/mtd/mtd0/mtd1
M: mtd1
R: 1
J: c90:2
U: mtd
T: mtd
D: c 90:2
N: mtd1
L: 0
S: mtd/by-name/u-boot
E: DEVPATH=/devices/platform/soc@14000000/14000000.spi/spi_master/spi0/spi0.0/mtd/mtd0/mtd1
E: DEVNAME=/dev/mtd1
E: DEVTYPE=mtd
E: OF_NAME=u-boot
E: OF_FULLNAME=/soc@14000000/spi@14000000/flash@0/partitions/u-boot@0
E: OF_COMPATIBLE_N=0
E: MAJOR=90
E: MINOR=2
E: SUBSYSTEM=mtd
E: USEC_INITIALIZED=17292618
E: NVME_HOST_IFACE=none
E: DEVLINKS=/dev/mtd/by-name/u-boot
E: TAGS=:systemd:
E: CURRENT_TAGS=:systemd:

Key differences :

1. DEVPATH: The partition mtd1 is a child of mtd0 in the sysfs hierarchy — .../mtd/mtd0/mtd1 vs .../mtd/mtd0
2. OF_FULLNAME: The master device points to the whole flash (/soc@.../flash@0), while the partition includes /partitions/ in its path (/soc@.../flash@0/partitions/u-boot@0)

[prajjwal-arista]

@chander-nexthop
here is the PR for updating the aspeed platform FW_ENV_DEFAULT var.
sonic-net/sonic-buildimage#29461

I dont see this ENV var being used in sonic-buildimage anywhere. Where is this used?
Do we have a hard dependency of both these PRs to go together?

[chander-nexthop]

@chander-nexthop here is the PR for updating the aspeed platform FW_ENV_DEFAULT var. sonic-net/sonic-buildimage#29461

I dont see this ENV var being used in sonic-buildimage anywhere. Where is this used? Do we have a hard dependency of both these PRs to go together?

No hard dependency, that was dangling reference and I thought its better to clean that up as any future use of that var will result in bugs with this change. Just request a follow up to ensure that PR too gets merged.