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

[Philippe Mathieu-Daudé]

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
> 
> Any ideas?

Richard hit that recently too.

Can you provide:

cat /proc/sys/vm/overcommit_kbytes
cat /proc/sys/vm/overcommit_memory
cat /proc/sys/vm/overcommit_ratio

and

cat /proc/meminfo

(CommitLimit, Committed_AS)

and OOM messages.

Per David, 'you can trick QEMU in trying to work around
that issue, specifying a memory-backend-ram with "reserve=off"
as guest RAM.'