Clearly there is no hurry here. This is more of a brainstorming issue than a proposal.

For:

• 64-bit ARM is the standard nowadays for the type of computing hardware our users tend to have (modern Raspberry Pi's and ARM servers). While 32-bit ARM is only still used in low-power embedded systems, an unlikely combination with a bitcoin node.

• 32-bit ARM is the last 32-bit architecture that we ship releases for. After removing this, we could fully focus on optimizing for large virtual address spaces. This means nearly-unrestricted mmap, and no need to worry about the virtual memory overhead of more thread stacks.

• Is it still being properly tested at all? If no one really cares, things could break without us noticing.

Against:

• There are likely still users that use 2010-era ARM boxes for their nodes, though the number is likely to be dwindling (mine certainly died by now).

• Requiring 64-bit even for self-built binaries is a step further, it might be wise to keep the 32-bit door open, at least i'm always hesitant with anything that limits potential hardware that can be used for bitcoin nodes.

  • OTOH we'd be in good company. Monero never supported 32-bit platforms for their node (because of using lmdb).

See also bitcoin-core/bitcoincore.org#1126, where the default was recently changed to 64-bit.