Re: xilinx-zynq-a9: cannot set up guest memory 'zynq.ext_ram'

[Peter Maydell]

On Fri, 20 Aug 2021 at 15:34, David Hildenbrand <david@redhat.com> wrote:
>
> On 20.08.21 16:22, Bin Meng wrote:
> > Hi Philippe,
> >
> > On Fri, Aug 20, 2021 at 10:10 PM Philippe Mathieu-Daudé
> > <philmd@redhat.com> wrote:
> >>
> >> Hi Bin,
> >>
> >> On 8/20/21 4:04 PM, Bin Meng wrote:
> >>> Hi,
> >>>
> >>> The following command used to work on QEMU 4.2.0, but is now broken
> >>> with QEMU head.
> >>>
> >>> $ qemu-system-arm -M xilinx-zynq-a9 -display none -m 40000000
> >>> -nographic -serial /dev/null -serial mon:stdio -monitor null -device
> >>> loader,file=u-boot-dtb.bin,addr=0x4000000,cpu-num=0
> >>> qemu-system-arm: cannot set up guest memory 'zynq.ext_ram': Cannot
> >>> allocate memory

> -m 40000000
>
> corresponds to 38 TB if I am not wrong. Is that really what you want?

Probably not, because the zynq board's init function does:

    if (machine->ram_size > 2 * GiB) {
        error_report("RAM size more than 2 GiB is not supported");
        exit(EXIT_FAILURE);
    }

It seems a bit daft that we allocate the memory before we do
the size check. This didn't use to be this way around...

Anyway, I think the cause of this change is commit c9800965c1be6c39
from Igor. We used to silently cap the RAM size to 2GB; now we
complain. Or at least we would complain if we hadn't already
tried to allocate the memory and fallen over...

-- PMM