On Wed, Jan 31, 2024 at 02:59:53PM -0800, Stephen Boyd wrote: > Quoting Rob Herring (2024-01-31 12:54:05) > > On Mon, Jan 29, 2024 at 04:45:00PM -0800, Stephen Boyd wrote: > > > Call this function unconditionally so that we can populate an empty DTB > > > on platforms that don't boot with a firmware provided or builtin DTB. > > > Override 'initial_boot_params' to NULL when ACPI is in use but the > > > bootloader has loaded a DTB so that we don't allow both ACPI and DT to > > > be used during boot. If there isn't a valid initial_boot_params dtb then > > > unflatten_device_tree() returns early so this is fine. > > > > > > Cc: Rob Herring <robh+dt@xxxxxxxxxx> > > > Cc: Frank Rowand <frowand.list@xxxxxxxxx> > > > Cc: Catalin Marinas <catalin.marinas@xxxxxxx> > > > Cc: Will Deacon <will@xxxxxxxxxx> > > > Cc: Mark Rutland <mark.rutland@xxxxxxx> > > > Cc: <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx> > > > Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxx> > > > --- > > > arch/arm64/kernel/setup.c | 7 +++++-- > > > 1 file changed, 5 insertions(+), 2 deletions(-) > > > > > > diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c > > > index 417a8a86b2db..ffb1942724ae 100644 > > > --- a/arch/arm64/kernel/setup.c > > > +++ b/arch/arm64/kernel/setup.c > > > @@ -351,8 +351,11 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p) > > > /* Parse the ACPI tables for possible boot-time configuration */ > > > acpi_boot_table_init(); > > > > > > - if (acpi_disabled) > > > - unflatten_device_tree(); > > > + /* Don't use the FDT from boot if ACPI is in use */ > > > + if (!acpi_disabled) > > > + initial_boot_params = NULL; > > > > I still think this is a problem for kexec. See > > of_kexec_alloc_and_setup_fdt(). You see it uses initial_boot_params. At > > first glance it looks like it would just write out everything we need. > > But for UEFI boot, I think we need all the chosen properties like > > linux,uefi-mmap-start preserved from the current boot for the next > > kernel we kexec. > > Ok, got it. > > > > > I think you'll have to check acpi_disabled in unflatten_device_tree() > > and unflatten the empty tree leaving initial_boot_params alone. That > > means our FDT and unflattened tree will be different DTs, but I think > > that's fine. > > It's sort of scary given that 'initial_boot_params' is an exported > global. Maybe that should be hidden away and accessed with a function > instead so that this mismatch doesn't break something later on? What you see now is after I did a pass of minimizing the number of users. BTW, I've now got another use for unconditionally calling unflatten_device_tree() with this[1]. Rob [1] https://lore.kernel.org/all/20240201194653.GA1328565-robh@xxxxxxxxxx/
