On Wed, Dec 17, 2025 at 10:40 AM Nathan Bossart <[email protected]> wrote: > Hm. I think the USE_LLVM_BACKPORT_SECTION_MEMORY_MANAGER thing might need > work, too. We don't have any Windows buildfarm machines with LLVM enabled, > but IIUC it should be possible. Perhaps we can add that to unicorn.
The LLVM code has never run on Windows and will likely need patching... I know of at least one change required and will write about that. > > Also, while the patch > > is targeting Windows 11 (IIUC), there are some notes in the docs that give > > the impression Windows 10 is supported, too [0]. I could easily change it > > to say that AArch64 requires Windows 11, but I don't know what to do with > > the references to specific versions of Visual Studio and the Windows SDK. > > Actually, I'm not sure there's anything specific to Windows 11 in this > patch, besides perhaps the choice to set USE_ARMV8_CRC32C unconditionally. > I don't know how likely it is that someone will try to run Postgres on > Windows on an AArch64 machine without CRC extension support, though. Assuming you haven't blocked OS updates, Windows stopped booting on pre-ARMv8.1 hardware a while back. RPi4's Broadcom chip and the Snapdragon 835 (found in the oldest Windows laptops, according to a quick Google search) are ARMv8-A only, but did actually have the CRC32 instructions, so it would actually work anyway. They also have the optional NEON SIMD stuff, which we use unconditionally: /* * We use the Neon instructions if the compiler provides access to them (as * indicated by __ARM_NEON) and we are on aarch64. While Neon support is * technically optional for aarch64, it appears that all available 64-bit * hardware does have it. Neon exists in some 32-bit hardware too, but we * could not realistically use it there without a run-time check, which seems * not worth the trouble for now. */ A single chip in this report lacked FEAT_CRC32, the X-Gene 1 from 2012: https://gpages.juszkiewicz.com.pl/arm-socs-table/arm-socs.html So I don't think it's worth worrying about, I was just mentioning the "Windows 11 requires CRC32, Windows 10 is dead" thing to avoid Greg being forced to waste time researching the missing feature test code :-) The reason Windows can't boot on old ARM chips probably has more to do with the modern atomics needed for decent lock performance, which every kernel wants.
