On Fri, 08 Nov 2019 10:04:47 PST (-0800), Peter Maydell wrote:
> On Fri, 8 Nov 2019 at 17:15, Alistair Francis <alistai...@gmail.com> wrote:
> >
> > On Fri, Nov 8, 2019 at 9:05 AM Palmer Dabbelt <pal...@sifive.com> wrote:
> > >
> > > The test finisher implements the reset command, which means it's a
> > > "sifive,test1" device. This is a backwards compatible change, so it's
> > > also a "sifive,test0" device. I copied the odd idiom for adding a
> > > two-string compatible field from the ARM virt board.
> > >
> > > Fixes: 9a2551ed6f ("riscv: sifive_test: Add reset functionality")
> > > Signed-off-by: Palmer Dabbelt <pal...@sifive.com>
> > > Signed-off-by: Palmer Dabbelt <pal...@dabbelt.com>
> > > ---
> > > hw/riscv/virt.c | 5 ++++-
> > > 1 file changed, 4 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
> > > index 23f340df19..74f2dce81c 100644
> > > --- a/hw/riscv/virt.c
> > > +++ b/hw/riscv/virt.c
> > > @@ -359,7 +359,10 @@ static void create_fdt(RISCVVirtState *s, const
struct MemmapEntry *memmap,
> > > nodename = g_strdup_printf("/test@%lx",
> > > (long)memmap[VIRT_TEST].base);
> > > qemu_fdt_add_subnode(fdt, nodename);
> > > - qemu_fdt_setprop_string(fdt, nodename, "compatible", "sifive,test0");
> > > + {
> > > + const char compat[] = "sifive,test1\0sifive,test0";
> >
> > Does this really work? Why not use qemu_fdt_setprop_cells()?
> >
> > Alistair
> >
> > > + qemu_fdt_setprop(fdt, nodename, "compatible", compat, sizeof(compat));
> > > + }
>
> qemu_fdt_setprop_cells() is for "set this property to
> contain this list of 32-bit integers" (and it does a byteswap
> of each 32-bit value from host to BE). That's not what
> you want for a string (or a string list, which is what
> we have here).
>
> Cc'ing David Gibson who's our device tree expert to see if there's
> a nicer way to write this. Oddly, given that it's used in the
> ubiquitous 'compatible' prop, the dtc Documentation/manual.txt
> doesn't say anything about properties being able to be
> 'string lists', only 'strings', '32 bit numbers', 'lists of
> 32-bit numbers' and 'byte sequences'. You have to dig through
> the header file comments to deduce that a string list is
> represented by a string with embedded NULs separating
> each list item.
I copied this from hw/arm/virt.c, but messed up. There they use
const char compat[] = "arm,armv8-timer\0arm,armv7-timer";
qemu_fdt_setprop(vms->fdt, "/timer", "compatible",
compat, sizeof(compat));
