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xen/arm64: introduce sys/arm64/include/xen/xen-os.h
AbandonedPublic

Authored by ehem_freebsd_m5p.com on Mar 30 2021, 6:52 PM.

Details

Reviewers
royger
mhorne
manu
Summary

Introduce the main header for conventional variations of Xen. Some
setups are unavailable on some hardware architectures. Some hardware
architectures require differing memory allocation types.

The original author of FreeBSD on Xen/ARM code brought the whole header
in as a large blob. Introducing this header earlier allows showing how
ARM varies from what x86 has.

The content was created in 2014, even though the Git expression of it
was created in 2021.

Diff Detail

Repository
rS FreeBSD src repository - subversion
Lint
Lint OK
Unit
No Unit Test Coverage
Build Status
Buildable 38185
Build 35074: arc lint + arc unit

Event Timeline

My thinking is, if this is brought in now then various commits could include both the x86 and ARM settings. Thus illustrating why those needed to be added. Notably, D29351, D29402, D29403, D29404, D29405, and D29406 all use distinct implementations for ARM.

The downside is this leaves a mysterious header hanging out in ARM64 land apparently doing nothing until the rest of Xen/ARM is operational.

mhorne requested changes to this revision.EditedMar 30 2021, 8:05 PM

My thinking is, if this is brought in now then various commits could include both the x86 and ARM settings. Thus illustrating why those needed to be added. Notably, D29351, D29402, D29403, D29404, D29405, and D29406 all use distinct implementations for ARM.

The downside is this leaves a mysterious header hanging out in ARM64 land apparently doing nothing until the rest of Xen/ARM is operational.

Although I understand your reasoning, I do not think this is the right way to handle this.

The reviews you linked are useful in their own right: they do the preliminary cleanups required to accommodate support for a new architecture. Adding the arm64 versions of those definitions is outside the scope of this, since that support doesn't exist yet in FreeBSD.

Introducing this header in such a piecemeal way will complicate the history. I would rather see it committed in its entirety alongside other relevant pieces of the arm64 xen support.

This revision now requires changes to proceed.Mar 30 2021, 8:05 PM

Now realizing I misunderstood Roger Pau Monné's comment, I basically agree with Mitchell Horne on his view. Even had I understood correctly on the first try, this approach was worthy of considering anyway.

I keep coming back and wondering if this really is the way things should be done. There are a bunch of commits which potentially merely add a line or two to this file and don't really own it. This would also serve as the marker for where the real implementation of Xen/ARM support starts in history.