Re: [Qemu-devel] [PATCH qemu] fdc: Exit if ISA controller does not support DMA

[Hervé Poussineau]

Le 08/12/2017 à 22:29, John Snow a écrit :
[...]
> It looks like Herve was working on decoupling floppies from i8257, but
> perhaps didn't get all the way through -- I'm not actually clear on what
> work remains to be done here, maybe he can chime in if he's still
> interested in the project?

Indeed, I worked on decoupling floppies (and other ISA devices) from i8257, for 
three reasons:
1) having a working floppy on MIPS Magnum machine. fdc is PC-compatible, but 
DMA controller is not i8257-compatible.
2) reimplement another ISA bus with a somewhat i8257-compatible DMA
3) for fun, support multiple ISA buses on a same machine but on different PCI 
bridges.

I failed on point 1), mostly due to lack of documentation.
I succeeded on point 2), by having locally some patches for a ISAPNP bus, where 
IO/IRQ/DMA addresses of ISA devices can change dynamically, and devices can be 
discovered by operating system.
About point 3, most of the patches are ready, but some details are still to be 
fixed.

Regards,

Hervé