On Thu, Dec 31, 2020 at 3:23 PM Vitaly Wool <vitaly.w...@konsulko.com> wrote: > > On Tue, Dec 29, 2020 at 6:05 AM Anup Patel <a...@brainfault.org> wrote: > > > > On Mon, Dec 28, 2020 at 10:08 PM Vitaly Wool <vitaly.w...@konsulko.com> > > wrote: > > > > > > On Mon, Dec 28, 2020 at 3:10 PM Anup Patel <a...@brainfault.org> wrote: > > > > > > > > On Mon, Dec 28, 2020 at 7:05 PM Vitaly Wool <vitaly.w...@konsulko.com> > > > > wrote: > > > > > > > > > > On Mon, Dec 28, 2020 at 12:59 PM Anup Patel <a...@brainfault.org> > > > > > wrote: > > > > > > > > > > > > On Sat, Dec 26, 2020 at 10:03 PM Vitaly Wool > > > > > > <vitaly.w...@konsulko.com> wrote: > > > > > > > > > > > > > > Sometimes, especially in a production system we may not want to > > > > > > > use a "smart bootloader" like u-boot to load kernel, ramdisk and > > > > > > > device tree from a filesystem on eMMC, but rather load the kernel > > > > > > > from a NAND partition and just run it as soon as we can, and in > > > > > > > this case it is convenient to have device tree compiled into the > > > > > > > kernel binary. Since this case is not limited to MMU-less systems, > > > > > > > let's support it for these which have MMU enabled too. > > > > > > > > > > > > > > Signed-off-by: Vitaly Wool <vitaly.w...@konsulko.com> > > > > > > > --- > > > > > > > arch/riscv/Kconfig | 1 - > > > > > > > arch/riscv/mm/init.c | 12 ++++++++++-- > > > > > > > 2 files changed, 10 insertions(+), 3 deletions(-) > > > > > > > > > > > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > > > > > > > index 2b41f6d8e458..9464b4e3a71a 100644 > > > > > > > --- a/arch/riscv/Kconfig > > > > > > > +++ b/arch/riscv/Kconfig > > > > > > > @@ -419,7 +419,6 @@ endmenu > > > > > > > > > > > > > > config BUILTIN_DTB > > > > > > > def_bool n > > > > > > > - depends on RISCV_M_MODE > > > > > > > depends on OF > > > > > > > > > > > > > > menu "Power management options" > > > > > > > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c > > > > > > > index 87c305c566ac..5d1c7a3ec01c 100644 > > > > > > > --- a/arch/riscv/mm/init.c > > > > > > > +++ b/arch/riscv/mm/init.c > > > > > > > @@ -194,12 +194,20 @@ void __init setup_bootmem(void) > > > > > > > setup_initrd(); > > > > > > > #endif /* CONFIG_BLK_DEV_INITRD */ > > > > > > > > > > > > > > + /* > > > > > > > + * If DTB is built in, no need to reserve its memblock. > > > > > > > + * OTOH, initial_boot_params has to be set to properly > > > > > > > copy DTB > > > > > > > + * before unflattening later on. > > > > > > > + */ > > > > > > > + if (IS_ENABLED(CONFIG_BUILTIN_DTB)) > > > > > > > + initial_boot_params = __va(dtb_early_pa); > > > > > > > > > > > > Don't assign initial_boot_params directly here because the > > > > > > early_init_dt_scan() will do it. > > > > > > > > > > early_init_dt_scan will set initial_boot_params to dtb_early_va from > > > > > the early mapping which will be gone by the time > > > > > unflatten_and_copy_device_tree() is called. > > > > > > > > That's why we are doing early_init_dt_verify() again for the MMU-enabled > > > > case which already takes care of your concern. > > > > > > I might be out in the woods here but... Do you mean the call to > > > early_init_dt_verify() in setup_arch() which is compiled out > > > completely in the CONFIG_BUILTIN_DTB case? > > > Or is there any other call that I'm overlooking? > > > > Sorry for the confusion, what I meant was that we are calling > > early_init_dt_verify() from setup_arch() for the MMU-enabled > > with built-in DTB disabled case to update "initial_boot_params" > > after the boot CPU has switched from early_pg_dir to swapper_pg_dir. > > > > For MMU-enabled with built-in DTB case, if setup_vm() sets the > > dtb_early_va and dtb_early_pa correctly then early_init_dt_scan() > > called from setup_arch() will automatically set correct value for > > "initial_boot_params". > > Oh I think I get it now. You are suggesting to skip the temporary > mapping for DT altogether since it is anyway in the kernel mapping > range, aren't you? > That does make sense indeed, thanks :)
Yes, that's what I am suggesting. > > > It is strange that early_init_dt_verify() is being compiled-out for you > > because the early_init_dt_scan() called from setup_arch() also uses > > early_init_dt_verify(). I quickly compiled the NoMMU kernel for K210 > > which also uses built-in DTB and I see that early_init_dt_verify() > > is not being compiled-out when built-in DTB is enabled. > > I did not say that early_init_dt_verify() is compiled out, it's the > call to it in setup_arch() that is compiled out if BUILTIN_DTB is > selected. However, if I understand you correctly now, it should not > matter if we don't set dtb_early_va to point to the temporary mapping. Yes, dtb_early_va can point to some other location such as built-in DTB. For MMU-enabled with built-in DTB case, the setup_vm() should skip the temporary mapping to DT and instead set dtb_early_va and dtb_early_pa to point to the built-in DTB. Regards, Anup
