Re: [PATCH v3 1/2] semihosting/arm-compat: replace heuristic for softmmu SYS_HEAPINFO

[Peter Maydell]

On Fri, 18 Jun 2021 at 11:09, Peter Maydell <peter.maydell@linaro.org> wrote:
>
> On Thu, 17 Jun 2021 at 20:22, Peter Maydell <peter.maydell@linaro.org> wrote:
> > This will pick the first MR it finds that happens to be RAM (which
> > could be some tiny thing). You don't want that, you want specifically
> > whatever the board decided was the system RAM, which is the MemoryRegion
> > MachineState::ram.
>
> As a concrete example, on the mps3-an547 machine this code finds
> the 512KB ITCM at 0x0 rather than the much more useful 2GB DRAM
> at 0x6000_0000...

Turns out that "look for MachineState::ram" won't find you the
2GB DRAM, though, because it's lurking behind a Memory Protection
Controller so it doesn't appear directly in the flatview.
Not sure what to do about that -- maybe we should forget about
MachineState::ram and just go for "largest RAM we can see" ?
Trying to get this code to be able to 'look through' IOMMUs sounds
like it would be massively painful.

-- PMM