Hi Michal,
> On 9 Jun 2022, at 10:57, Michal Orzel via lists.yoctoproject.org
> <[email protected]> wrote:
>
> By default, highmem option is enabled for machine types later than
> virt-2.12. This allows qemu to place devices and RAM in physical
> address space above 32-bits. This can cause issues as according to the
> documentation Xen supports up to 12GiB of physical address space.
> Recently the issue was observed using runqemu, that was causing Linux
> running on top of Xen to stall when trying to access ECAM space placed
> by qemu at 256GiB mark. Even though this issue is most probably related
> to QEMU and not Xen (the investigation showed that it can map ECAM
> space correctly), it is best to avoid such issues by disabling highmem
> on qemuarm.
>
> Signed-off-by: Michal Orzel <[email protected]>
Reviewed-by: Bertrand Marquis <[email protected]>
Also tested on kirkstone and dom0 boots fine and pci is working.
Thanks a lot
Cheers
Bertrand
> ---
> classes/qemuboot-xen-defaults.bbclass | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/classes/qemuboot-xen-defaults.bbclass
> b/classes/qemuboot-xen-defaults.bbclass
> index f1550cc..460cbe6 100644
> --- a/classes/qemuboot-xen-defaults.bbclass
> +++ b/classes/qemuboot-xen-defaults.bbclass
> @@ -23,8 +23,10 @@ QB_DEFAULT_KERNEL:qemuarm = "xen-${MACHINE}"
>
> # 64-bit Arm: gic version 3
> QB_MACHINE:qemuarm64 = "-machine virt,gic-version=3 -machine
> virtualization=true"
> -# 32-bit Arm
> -QB_MACHINE:qemuarm = "-machine virt -machine virtualization=true"
> +# 32-bit Arm: highmem=off
> +# Disable highmem so that qemu does not use highmem IO regions that end up
> +# being placed at the 256GiB mark (e.g. ECAM space) and can cause issues in
> Xen.
> +QB_MACHINE:qemuarm = "-machine virt,highmem=off -machine virtualization=true"
>
> # Increase the default qemu memory allocation to allow for the hypervisor.
> # Use a weak assignment to allow for change of default and override elsewhere.
> --
> 2.25.1
>
>
>
>
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