Re: [RFC] disk/part: partition number parsed as hex in blk_get_device_part_str

Hi Tom,

On 8/10/26 6:02 PM, Tom Rini wrote:
> On Mon, Aug 10, 2026 at 03:34:48PM +0200, Quentin Schulz wrote:
>> Hi Albin,
>>
>> On 8/10/26 1:43 PM, Raj, Albin via U-Boot wrote:
>>> Hello,
>>>
>>> While testing GPT partitions on USB media, I noticed that partition identifiers passed on the command line appear to be parsed as hexadecimal values.
>>>
>>> Example:
>>>
>>> => part list usb 0
>>>
>>> Partition Map for USB device 0  --   Partition Type: EFI
>>>
>>> Part    Start LBA       End LBA         Name
>>>           Attributes
>>>           Type GUID
>>>           Partition GUID
>>>     1     0x00000800      0x008007ff      ""
>>>           attrs:  0x0000000000000000
>>>           type:   0fc63daf-8483-4772-8e79-3d69d8477de4
>>>           guid:   5d33e1b1-c3ae-4e58-8677-13a295ce7b41
>>>     2     0x00800800      0x010007ff      ""
>>>           attrs:  0x0000000000000000
>>>           type:   0fc63daf-8483-4772-8e79-3d69d8477de4
>>>           guid:   277f159b-1239-4be1-bc1e-54c718331584
>>>     3     0x01000800      0x018007ff      ""
>>>           attrs:  0x0000000000000000
>>>           type:   0fc63daf-8483-4772-8e79-3d69d8477de4
>>>           guid:   470b684e-6d99-4a26-866f-14663b13dcbf
>>>     4     0x01800800      0x020007ff      ""
>>>           attrs:  0x0000000000000000
>>>           type:   0fc63daf-8483-4772-8e79-3d69d8477de4
>>>           guid:   1f598bf7-5d31-47bf-9a1d-75c2c6b74dd4
>>>     5     0x02000800      0x028007ff      ""
>>>           attrs:  0x0000000000000000
>>>           type:   0fc63daf-8483-4772-8e79-3d69d8477de4
>>>           guid:   30491f52-e2d7-4f15-8925-92c00ca6e8fb
>>>     6     0x02800800      0x030007ff      ""
>>>           attrs:  0x0000000000000000
>>>           type:   0fc63daf-8483-4772-8e79-3d69d8477de4
>>>           guid:   aef06b97-9320-494b-bff9-3f2cb472ba7f
>>>     7     0x03000800      0x038007ff      ""
>>>           attrs:  0x0000000000000000
>>>           type:   0fc63daf-8483-4772-8e79-3d69d8477de4
>>>           guid:   74143690-f5ab-4437-949e-b098199435c3
>>>     8     0x03800800      0x040007ff      ""
>>>           attrs:  0x0000000000000000
>>>           type:   0fc63daf-8483-4772-8e79-3d69d8477de4
>>>           guid:   fca32ea9-8165-404a-8eac-b22b80a15c8a
>>>     9     0x04000800      0x048007ff      ""
>>>           attrs:  0x0000000000000000
>>>           type:   0fc63daf-8483-4772-8e79-3d69d8477de4
>>>           guid:   fd4d818b-205e-43ef-9de5-7be6bf8550c8
>>> 10     0x04800800      0x050007ff      ""
>>>           attrs:  0x0000000000000000
>>>           type:   0fc63daf-8483-4772-8e79-3d69d8477de4
>>>           guid:   a4b21c4c-f0cf-4fb7-b70a-0f191b9fd874
>>> 11     0x05000800      0x058007ff      ""
>>>           attrs:  0x0000000000000000
>>>           type:   0fc63daf-8483-4772-8e79-3d69d8477de4
>>>           guid:   243ae3ce-4fd5-4230-ba83-137d8655ea8c
>>> 12     0x05800800      0x060007ff      ""
>>>           attrs:  0x0000000000000000
>>>           type:   0fc63daf-8483-4772-8e79-3d69d8477de4
>>>           guid:   671bdeba-dd6a-43e0-a99c-e880ebab991b
>>> 13     0x06000800      0x068007ff      ""
>>>           attrs:  0x0000000000000000
>>>           type:   0fc63daf-8483-4772-8e79-3d69d8477de4
>>>           guid:   b5fd6923-e40b-4018-9808-541c91ec81f5
>>> 14     0x06800800      0x070007ff      ""
>>>           attrs:  0x0000000000000000
>>>           type:   0fc63daf-8483-4772-8e79-3d69d8477de4
>>>           guid:   29634671-56d8-45f7-8a22-f2b7c33520a5
>>>
>>>
>>> Partition 9 can be accessed successfully:
>>>
>>> => part uuid usb 0:9
>>> fd4d818b-205e-43ef-9de5-7be6bf8550c8
>>>
>>> However:
>>>
>>> => part uuid usb 0:10
>>> ** Invalid partition 16 **
>>>
>>> => part uuid usb 0:11
>>> ** Invalid partition 17 **
>>>
>>> Looking at blk_get_device_part_str() the partition number is parsed with:
>>>
>>>       part = (int)hextoul(part_str, &ep);
>>>
>>> which converts:
>>>
>>>       10 -> 16
>>>       11 -> 17
>>>
>>> Since "part list" displays partition identifiers in decimal, users reasonably expect "0:10" to refer to partition 10 rather than partition 16.
>>>
>>> Is this behavior intentional for backward compatibility, or would decimal parsing be preferred?
>>>
>>
>> We will not change the parsing of numbers for existing commands, as you
>> guessed, for backward compatibility. However, we certainly could document it
>> explicitly in https://docs.u-boot-project.org/en/latest/usage/cmd/part.html
>> (which you can change in our source tree in doc/usage/cmd/part.rst).
> 
> It should be clear in the general documentation as all inputs (with a
> few rare exceptions such as "sleep") take hexadecimal.
> 

Being pedantic here:

https://docs.u-boot-project.org/en/latest/usage/index.html#shell-commands 
says "For all commands in U-Boot there are some General rules that apply.".

https://docs.u-boot-project.org/en/latest/usage/cmdline.html#general-rules 
doesn't mention anything about the base for numbers in commands.

However, 
https://docs.u-boot-project.org/en/latest/usage/cmdline.html#representing-numbers 
does, but it's at the same level as 
https://docs.u-boot-project.org/en/latest/usage/cmdline.html#general-rules 
so while the user may read what's after General Rules, it's visually a 
different and unrelated topic.

Cheers,
Quentin