m-labs/misoc

fix or remove Ultrascale SDRAM init

sbourdeauducq opened this issue · 4 comments

sbourdeauducq commented

Since the SDRAM initialization is no longer regularly tested (as the Rust bootloader is used instead), it has stopped working on Sayma.
Options are:

  • remove the BIOS completely; this means removing LM32 since there is no usable Rust toolchain for it.
  • remove Ultrascale SDRAM support from MiSoC
  • fix the BIOS on Sayma
jbqubit commented

I don't fully understand the implications of these different paths. Are you proposing switching LM32 to mor1kx? Where would Ultrascale SDRAM support be housed if not in MiSoC? What caused it to stop working?

sbourdeauducq commented

ARTIQ 4 no longer uses the MiSoC bootloader, and Ultrascale development continued in the ARTIQ bootloader but the changes were not ported to the MiSoC bootloader.

jbqubit commented

Since Sayma support is part of ARTIQ 4 it seems like Sayma ought to also use the ARTIQ 4 bootloader. What are the prospects for this port?

whitequark commented

Sayma uses the ARTIQ 4 bootloader currently (and there's no particular reason I know for it to go back). The Ultrascale SDRAM code in MiSoC could be useful for other people who use MiSoC on Ultrascale, not that any necessarily exist.

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