Re: [PATCH v1 5/5] xen/riscv: map FDT

[Julien Grall <julien@xxxxxxx>]

Hi,

On 11/07/2024 10:40, Oleksii wrote:
> On Wed, 2024-07-10 at 14:38 +0200, Jan Beulich wrote:
> > On 03.07.2024 12:42, Oleksii Kurochko wrote:
> > > Except mapping of FDT, it is also printing command line passed by
> > > a DTB and initialize bootinfo from a DTB.
> > I'm glad the description isn't empty here. However, ...
> >
> > > --- a/xen/arch/riscv/riscv64/head.S
> > > +++ b/xen/arch/riscv/riscv64/head.S
> > > @@ -41,6 +41,9 @@ FUNC(start)
> > >   
> > >           jal     setup_initial_pagetables
> > >   
> > > +        mv      a0, s1
> > > +        jal     fdt_map
> > > +
> > >           /* Calculate proper VA after jump from 1:1 mapping */
> > >           la      a0, .L_primary_switched
> > >           sub     a0, a0, s2
> > ... it could do with clarifying why this needs calling from assembly
> > code. Mapping the FDT clearly looks like something that wants doing
> > from start_xen(), i.e. from C code.
> fdt_map() expected to work while MMU is off as it is using
> setup_initial_mapping() which is working with physical address.
Somewhat related to what Jan is asking. You only seem to part the FDT in 
start_xen(). So why do you need to call fdt_map() that early?
Cheers,

--
Julien Grall