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patches/openwrt: mpc85xx: support and use SPE float instructions

Simon Borek requested to merge feature/mpc85xx-hardware-SPE-float-support_HBD_kernel-5.10 into hbd

This is needed for Turris 1.x uboot compilation that is failing if soft float ABI is used.

The usage of SPE1 ISA extension allows CPUs with PowerPC e500v2 cores (used in Turris 1.x routers) to perform native operations on single2 and double precision floats stored in GPRs3 as well as vector operations using the whole 64-bit size of CPU registers (whose upper 32 bits are inaccessible otherwise).4

In the current state it's possible router will crash just after performing the update to this branch unable to reboot itself properly (without manual power disconnection) - needs fix before merge to HBL.

  1. signal processing engine ↩

  2. applies to e500v1 as well ↩

  3. general purpose registers ↩

  4. https://www.nxp.com/docs/en/reference-manual/SPEPEM.pdf ↩

Edited by Simon Borek

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