Re: Porting to Snapdragon 8cx SoC

I submitted a pull request to handle ACPI devices as handled in the OpenBSD
source tree.

https://github.com/freebsd/freebsd-src/pull/1971

On Mon, Jan 12, 2026 at 6:47 PM Mark Millard <marklmi@yahoo.com> wrote:

> On 1/12/26 15:42, Mark Millard wrote:
> > 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
> >
> >
> >
>
> Not my day, trying for the right URL this time . . .
>
> <
> https://cgit.freebsd.org/src/commit/?id=8793196ca28f7b78f04ca479fe60b7d7af6b20e1
> >
>
> --
> ===
> Mark Millard
> marklmi at yahoo.com
>
>