[PATCH 2/5] qemu-arm: Get bloblist from boot arguments

[Raymond Mao]

Hi Michal,
Yes, I can put this part as armv8/v7 common functions.

Thanks and regards,
Raymond

On Wed, 20 Dec 2023 at 06:03, Michal Simek <michal.simek at amd.com> wrote:

>
>
> On 12/19/23 22:11, Raymond Mao wrote:
> > Add platform custom function to get bloblist from boot arguments.
> > Check whether boot arguments aligns with the register conventions
> > defined in FW Handoff spec v0.9.
> > Add bloblist related options into qemu default config.
> >
> > Signed-off-by: Raymond Mao <raymond.mao at linaro.org>
> > ---
> >   board/emulation/qemu-arm/Makefile        |  1 +
> >   board/emulation/qemu-arm/lowlevel_init.S | 19 +++++++++
> >   board/emulation/qemu-arm/qemu-arm.c      | 51 ++++++++++++++++++++++++
> >   configs/qemu_arm64_defconfig             |  3 ++
> >   4 files changed, 74 insertions(+)
> >   create mode 100644 board/emulation/qemu-arm/lowlevel_init.S
> >
> > diff --git a/board/emulation/qemu-arm/Makefile
> b/board/emulation/qemu-arm/Makefile
> > index a22d1237ff..0eb262e4e2 100644
> > --- a/board/emulation/qemu-arm/Makefile
> > +++ b/board/emulation/qemu-arm/Makefile
> > @@ -1,3 +1,4 @@
> >   # SPDX-License-Identifier: GPL-2.0+
> >
> >   obj-y       += qemu-arm.o
> > +obj-y        += lowlevel_init.o
> > diff --git a/board/emulation/qemu-arm/lowlevel_init.S
> b/board/emulation/qemu-arm/lowlevel_init.S
> > new file mode 100644
> > index 0000000000..d72d7c938a
> > --- /dev/null
> > +++ b/board/emulation/qemu-arm/lowlevel_init.S
> > @@ -0,0 +1,19 @@
> > +/* SPDX-License-Identifier: BSD-2-Clause */
> > +/*
> > + * Copyright (c) 2023, Linaro Limited
> > + */
> > +
> > +#include <config.h>
> > +
> > +.global save_boot_params
> > +save_boot_params:
> > +#ifdef CONFIG_ARM64
> > +     adr x9, qemu_saved_args
> > +     stp x0, x1, [x9]
> > +     /* Increment the address by 16 bytes for the next pair of values */
> > +     stp x2, x3, [x9, #16]
>
> There is specified how transfer list should be passed from one stage to
> another.
> Which pretty much saying that when bloblist is enabled this is what you
> can
> expect on arm64.
> Why not to add it directly to?
> arch/arm/cpu/armv8/start.S
>
> WEAK(save_boot_params)
> #if bloblist
>         (your code)
> #endif
>         b       save_boot_params_ret    /* back to my caller */
> ENDPROC(save_boot_params)
>
> because pretty much all platforms which want to switch to it will just c&p
> your
> code.
>
> that being said qemu_saved_args can become just generic save_args and you
> can
> also allocate space in .data section in this file.
>
> > +#else
> > +     ldr r12, =qemu_saved_args
> > +     stm r12, {r0, r1, r2, r3}
>
> And this part should go to arch/arm/cpu/armv7/start.S
>
> M
>