Re: [PATCH v1 4/6] riscv/sifive_u: Add the start-in-flash property

[Bin Meng]

On Sat, Sep 21, 2019 at 6:12 AM Alistair Francis <address@hidden> wrote:
>
> On Thu, Sep 19, 2019 at 10:15 PM Bin Meng <address@hidden> wrote:
> >
> > On Fri, Sep 20, 2019 at 6:32 AM Alistair Francis
> > <address@hidden> wrote:
> > >
> > > Add a property that when set to true QEMU will jump from the ROM code to
> > > the start of flash memory instead of DRAM which is the default
> > > behaviour.
> > >
> > > Signed-off-by: Alistair Francis <address@hidden>
> > > ---
> > >  hw/riscv/sifive_u.c         | 27 +++++++++++++++++++++++++++
> > >  include/hw/riscv/sifive_u.h |  2 ++
> > >  2 files changed, 29 insertions(+)
> > >
> > > diff --git a/hw/riscv/sifive_u.c b/hw/riscv/sifive_u.c
> > > index c3949fb316..b7cd3631cd 100644
> > > --- a/hw/riscv/sifive_u.c
> > > +++ b/hw/riscv/sifive_u.c
> > > @@ -373,6 +373,10 @@ static void riscv_sifive_u_init(MachineState 
> > > *machine)
> > >                                         /* dtb: */
> > >      };
> > >
> > > +    if (s->start_in_flash) {
> > > +        reset_vec[6] = memmap[SIFIVE_U_FLASH0].base; /* start: .dword 
> > > FLASH0_BASE */
> > > +    }
> > > +
> > >      /* copy in the reset vector in little_endian byte order */
> > >      for (i = 0; i < sizeof(reset_vec) >> 2; i++) {
> > >          reset_vec[i] = cpu_to_le32(reset_vec[i]);
> > > @@ -544,8 +548,31 @@ static void riscv_sifive_u_soc_realize(DeviceState 
> > > *dev, Error **errp)
> > >          memmap[SIFIVE_U_GEM_MGMT].base, memmap[SIFIVE_U_GEM_MGMT].size);
> > >  }
> > >
> > > +static bool virt_get_start_in_flash(Object *obj, Error **errp)
> > > +{
> > > +    SiFiveUState *s = RISCV_U_MACHINE(obj);
> > > +
> > > +    return s->start_in_flash;
> > > +}
> > > +
> > > +static void virt_set_start_in_flash(Object *obj, bool value, Error 
> > > **errp)
> > > +{
> > > +    SiFiveUState *s = RISCV_U_MACHINE(obj);
> > > +
> > > +    s->start_in_flash = value;
> > > +}
> > > +
> > >  static void riscv_sifive_u_machine_instance_init(Object *obj)
> > >  {
> > > +    SiFiveUState *s = RISCV_U_MACHINE(obj);
> > > +
> > > +    s->start_in_flash = false;
> > > +    object_property_add_bool(obj, "start-in-flash", 
> > > virt_get_start_in_flash,
> > > +                             virt_set_start_in_flash, NULL);
> > > +    object_property_set_description(obj, "start-in-flash",
> > > +                                    "Set on to tell QEMU's ROM to jump 
> > > to " \
> > > +                                    "flash. Otherwise QEMU will jump to 
> > > DRAM",
> > > +                                    NULL);
> > >
> > >  }
> > >
> > > diff --git a/include/hw/riscv/sifive_u.h b/include/hw/riscv/sifive_u.h
> > > index a921079fbe..2656b43c58 100644
> > > --- a/include/hw/riscv/sifive_u.h
> > > +++ b/include/hw/riscv/sifive_u.h
> > > @@ -57,6 +57,8 @@ typedef struct SiFiveUState {
> > >
> > >      void *fdt;
> > >      int fdt_size;
> > > +
> > > +    bool start_in_flash;
> > >  } SiFiveUState;
> > >
> > >  enum {
> >
> > This patch chose a different way from the one used in patch "[v1,6/6]
> > riscv/virt: Jump to pflash if specified":
> >
> > - this patch uses reset_vec[6] while patch [6/6] defines a variable 
> > start_addr
> > - this patch adds a "start-in-flash" property to the machine, while
> > patch [6/6] tests against drive IF_PFLASH
>
> Yes, we do it differently for the sifive_u board as the sifive_u board
> doesn't use pflash so there is no way to know if the user has loaded
> anything into the SPI memory.
>

OK.

> >
> > We should be consistent and I would prefer to use the patch [6/6] way.
> > On Unleashed an SPI flash is mounted so we cannot add a PFlash to
> > sifive_u machine like what was done on virt machine, so we should test
> > IF_MTD instead. Thoughts?
>
> How would we test that?
>
> Right now I am loading the binary in SPI with the -device loader
> option. The machine can't really know what is/isn't loaded there.
>
> It's not ideal, but I don't see a nicer way.

I think we need write a SiFive SPI model to support this in a clean
way. Ideally we should simulate the hardware boot workflow as
documented in the FU540 manual chapter 6 "Boot Process".

Regards,
Bin