On Wed, Jan 25, 2023 at 6:13 AM Alexandre Ghiti <alexghiti@xxxxxxxxxxxx> wrote:
>
> On Wed, Jan 25, 2023 at 11:41 AM Andrew Jones <ajones@xxxxxxxxxxxxxxxx> wrote:
> >
> > On Mon, Jan 23, 2023 at 03:25:54PM +0100, Andrew Jones wrote:
> > > On Mon, Jan 23, 2023 at 12:28:02PM +0100, Alexandre Ghiti wrote:
> > > > During the early page table creation, we used to set the mapping for
> > > > PAGE_OFFSET to the kernel load address: but the kernel load address is
> > > > always offseted by PMD_SIZE which makes it impossible to use PUD/P4D/PGD
> > > > pages as this physical address is not aligned on PUD/P4D/PGD size (whereas
> > > > PAGE_OFFSET is).
[...]
> > > > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> > > > index f08b25195ae7..58107bd56f8f 100644
> > > > --- a/drivers/of/fdt.c
> > > > +++ b/drivers/of/fdt.c
> > > > @@ -891,12 +891,13 @@ const void * __init of_flat_dt_match_machine(const void *default_match,
> > > > static void __early_init_dt_declare_initrd(unsigned long start,
> > > > unsigned long end)
> > > > {
> > > > - /* ARM64 would cause a BUG to occur here when CONFIG_DEBUG_VM is
> > > > - * enabled since __va() is called too early. ARM64 does make use
> > > > - * of phys_initrd_start/phys_initrd_size so we can skip this
> > > > - * conversion.
> > > > + /*
> > > > + * __va() is not yet available this early on some platforms. In that
> > > > + * case, the platform uses phys_initrd_start/phys_initrd_size instead
> > > > + * and does the VA conversion itself.
> > > > */
> > > > - if (!IS_ENABLED(CONFIG_ARM64)) {
> > > > + if (!IS_ENABLED(CONFIG_ARM64) &&
> > > > + !(IS_ENABLED(CONFIG_RISCV) && IS_ENABLED(CONFIG_64BIT))) {
> > >
> > > There are now two architectures, so maybe it's time for a new config
> > > symbol which would be selected by arm64 and riscv64 and then used here,
> > > e.g.
> > >
> > > if (!IS_ENABLED(CONFIG_NO_EARLY_LINEAR_MAP)) {
> >
> > I see v5 left this as it was. Any comment on this suggestion?
>
> Introducing a config for this only use case sounds excessive to me,
> but I'll let Rob decide what he wants to see here.
Agreed. Can we just keep it as is here.
> > > > initrd_start = (unsigned long)__va(start);
> > > > initrd_end = (unsigned long)__va(end);
I think long term, we should just get rid of needing to do this part
in the DT code and let the initrd code do this.
Rob
