Itanium IA-64 Was Busted In The Upstream, Default Linux Kernel Build The Past Month

While Intel formally discontinued the Itanium processors just under two years ago, the Linux software support for IA-64 continues. However, as a possible sign of the times, the Linux 5.11 kernel build for it has been broken the past month.

As what might set off Linus Torvalds on a Monday morning, it turns out since the Linux 5.11 merge window the Itanium "IA64" kernel code has been broken and unable to even successfully carry out a "defconfig" default configuration kernel build. This wasn't due to some foreign change within the kernel regressing the support but a change made by IBM to the IA64 Kconfig to enable SPARSEMEM by default.

While that change has been in the Linux kernel the past month with the Linux 5.11 merge window prior to Christmas, apparently no one tested it with the default configuration kernel build as it breaks due to a missing include file in the code. Presumably the code was at least built previously during testing but not in the plain vanilla default configuration.

The build failure from this IA64 memory model change was ultimately noted by the developer making the original change and is now awaiting a pull by Linus Torvalds for restoring the build support in Linux 5.11.