Re: [PATCH qemu v20] spapr: Implement Open Firmware client interface

[BALATON Zoltan <balaton@eik.bme.hu>]

On Thu, 20 May 2021, Alexey Kardashevskiy wrote:
> diff --git a/hw/ppc/spapr_vof.c b/hw/ppc/spapr_vof.c
> new file mode 100644
> index 000000000000..5e34d5402abf
> --- /dev/null
> +++ b/hw/ppc/spapr_vof.c
> @@ -0,0 +1,156 @@
> +/*
> + * SPAPR machine hooks to Virtual Open Firmware,
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +#include "qemu/osdep.h"
> +#include "qemu-common.h"
> +#include <sys/ioctl.h>
> +#include "qapi/error.h"
> +#include "hw/ppc/spapr.h"
> +#include "hw/ppc/spapr_vio.h"
> +#include "hw/ppc/fdt.h"
> +#include "sysemu/sysemu.h"
> +#include "qom/qom-qobject.h"
> +#include "trace.h"
> +
> +/* Copied from SLOF, and 4K is definitely not enough for GRUB */
> +#define OF_STACK_SIZE       0x8000

I found a reference explaining its value better than the comment above. 
Section 8.2.2 here:

https://www.devicetree.org/open-firmware/bindings/ppc/release/ppc-2_1.html

says it should be at least 32k. This define should be in vof.h so I don't 
have to duplicate it in pegasos2.c. Or vof_init could allocate and claim 
the stack so board code doesn't have to do that either. Maybe taking a 
pointer argument for preferred stack address as input and could return 
the aligned address where the stack was allocated or just store stack_base 
in struct vof where tha board code could get it for adding to r1 on 
calling the guest code.

Regards,
BALATON Zoltan