Re: Porting to Snapdragon 8cx SoC

On 1/12/26 15:33, Mark Millard wrote:
> On 1/12/26 15:09, Mark Millard wrote:
>> On 1/12/26 12:57, Gabe Bauer wrote:
>>> Hello, community! I am reaching out because I have a Thinkpad X13s with
>>> a Snapdragon 8cx Gen 3 SoC. I have been unable to get any operating
>>> system to work so far on this machine. I have done a fair amount of
>>> coding and debugging in C. However, I have never ported an operating
>>> system before. I am in my senior year at university and I would like to
>>> undertake this as a project. I have an x86_64 machine running FreeBSD
>>> which I can use to help me in this endeavour. However, since I have
>>> never done this before, I lack the domain specific knowledge on what I
>>> will need in order to be successful. Any tips on how to get started
>>> would be greatly appreciated. Thank you very much!!
>>
>>
>> Well, the Windows Dev Kit 2023 used(/uses) a Snapdragon 8cx Gen 3 SoC
>> and has a UEFI/ACPI that FreeBSD boots just fine. But FreeBSD does not
>> support the 2 USB-C ports in the result. It does support the 3 USB-A
>> ports, including booting from USB-A ports. (Some UEFI configuration
>> required to make that the default. I leave the internal drive with
>> Windows 11 Pro, forming the local Windows on aarch64 example when booted
>> that way.)
>>
>> But, in the FreeBSD based Dev Kit 20023 context, the UEFI/ACPI that is
>> built-in has the Snapdragon 8cx Gen 3 SoC related magic in it instead of
>> in the FreeBSD kernel, if I understand right.
>>
>> The UEFI/ACPI source code is not public as far as I know.
>>
>>
>> The Snapdragon 8cx Gen 3 SoC presents as having:
>>
>> 4 Cortex-A78C
>> and
>> 4 Cortex-X1C
>>
>>
>> FreeBSD does report the following relative to the ACPI and what FreeBSD
>> does not handle:
>>
>> ACPI Error: AE_NOT_FOUND, While resolving a named reference package
>> element - \134_SB_.UBF0.PRT0 (20251212/dspkginit-605)
>> ACPI Error: AE_NOT_FOUND, While resolving a named reference package
>> element - \134_SB_.UBF0.PRT1 (20251212/dspkginit-605)
>> . . .
>> ACPI Warning: \134_SB.GPU0._CLS: Return Package is too small - found 1
>> elements, expected 3 (20251212/nsprepkg-511)
>> can't fetch resources for \134_SB_.ADC1 - AE_AML_INVALID_RESOURCE_TYPE
>> acpi0: Could not update all GPEs: AE_NOT_CONFIGURED
>>
>> The 2 "ACPI Error" messages may well be tied to the 2 USB-C ports.
>>
>>
> 
> Looking around, the following are the commits that reference the Windows
> Dev Kit 2023. The older ones may give hints at what was required to get
> the FreeBSD kernel to boot based on the UEFI/ACPI involved.
> 
> 
> Commit message
> Author	Age	Files	Lines
> Commit URL
> 
> lib/libmd: add optimised SHA1 implementations for aarch64
> Robert Clausecker	2025-05-14	2	-0/+514
> https://cgit.freebsd.org/src/commit/?id=f6210541f9e3c6cfda321e0ad98f277fb98a625b
> 
> libc/aarch64: fix strlen() when flush-to-zero is set
> Robert Clausecker	2025-01-16	1	-2/+1
> https://cgit.freebsd.org/src/commit/?id=521c1fe0e2002dfd7d8db86eb7144b7865229912
> 
> arm64: Enable the Hyper-V keyboard driver
> Andrew Turner	2023-06-21	1	-0/+2
> https://cgit.freebsd.org/src/commit/?id=3a1bfe881a24a76ff8d6406476461924a027ea8a
> 
> arm64: Disable PAC when booting on a Windows Dev Kit 2023
> Mark Johnston	2023-04-23	1	-1/+30
> https://cgit.freebsd.org/src/commit/?id=4b39a12830feaf2ac49b157ed079c04114b1a3ca
> 
> Add CPU Ident for Qualcomm Kryo 400 (used in MS Dev Kit)
> Allan Jude	2023-01-18	2	-1/+14
> https://cgit.freebsd.org/src/commit/?id=fd5e9210598cfafbecc05b5ec03da25483833f90
> 
> Add the fixed memory type to the pci ecam driver
> Andrew Turner	2023-01-18	1	-3/+20
> https://cgit.freebsd.org/src/commit/?id=896f556205c8d87ef842dc844752daa7d2385336
> 
> loader.efi: make sure kernel image is executable
> Robert Clausecker	2023-01-05	1	-4/+4
> https://cgit.freebsd.org/src/commit/?id=95fa2e0aee5b7259cf4bcdea7396c4dff3241173
> 
> Add Windows Dev Kit 2023 support to if_ure
> Andrew Turner	2023-01-04	2	-0/+2
> https://cgit.freebsd.org/src/commit/?id=e5b9b5ee8c3a4f3bff348cd94e3555e6b69585f6
> 
> Check for more XHCI ACPI IDs
> Andrew Turner	2023-01-04	1	-4/+7
> https://cgit.freebsd.org/src/commit/?
> id=8793196ca28f7b78f04ca479fe60b7d7af6b20e1
> 
> 

I see that last URL ended up split. Trying an alternate notation to see
if it avoids that:

<https://cgit.freebsd.org/src/commit/?id=e5b9b5ee8c3a4f3bff348cd94e3555e6b69585f6>


-- 
===
Mark Millard
marklmi at yahoo.com