The future of 32-bit Linux

Posted Dec 8, 2020 8:52 UTC (Tue) by arnd (subscriber, #8866)
In reply to: The future of 32-bit Linux by mithro
Parent article: The future of 32-bit Linux

Right, when dealing with a small RV32I core comparable to a 1990s ARM7 or i386, going to 64 bits is out of the question. Once you get to bigger FPGAs and add in M, A, F, D, C and V extensions, as well go to larger caches, TLBs, and pipelines, the core is more like a Cortex-A7 or an early Intel Atom, so going to 64 bit is only a small step.

For the smallest cores, you'd also leave out the MMU and run some other OS that correspond to a modern take on µCLinux-2.0, but the interesting spot to watch is everything in between -- how big does an FPGA core have to be to make Linux-5.x the OS of choice without getting so big that you want to go straight to 64-bit Linux, and how long does it take before that niche disappears.

The future of 32-bit Linux

Posted Dec 8, 2020 17:54 UTC (Tue) by mithro (subscriber, #50469) [Link]

Due to plentify block ram in most modern FPGAs, an MMU implementation on an FPGA can actually be pretty cheap.

At the moment a <$100 USD FPGA dev board with <1 gigabytes RAM can be purchased that a 32bit Linux + MMU is *significantly* smaller and faster than 64bit. Due to the newer FPGAs mostly been focused on the datacenter use case and thus in the >$500 USD per FPGA IC, I don't see this changing for at least another 5ish years.