Linux 5.15 In 2021 Is Still Improving Intel 486 Era Hardware Support
In particular, some old Intel and ALi hardware is seeing some work done for this modern Linux kernel. Thomas Gleixner explained with the x86/irq pull request:
A set of updates to support port 0x22/0x23 based PCI configuration space which can be found on various ALi chipsets and is also available on older Intel systems which expose a PIRQ router. While the Intel support is more or less nostalgia, the ALi chips are still in use on popular embedded boards used for routers.
The PIRQ router work is for the ALi M1487 while on the Intel side the affected hardware is the 82374EB/82374SB and 82426EX, all from the Intel 486 days.
More details for those interested in vintage hardware via the pull request.