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@kernel.org Cc: Frank Rowand frowand.list@gmail.com Cc: Catalin Marinas catalin.marinas@arm.com Cc: Will Deacon will@kernel.org Cc: Mark Rutland mark.rutland@arm.com Cc: linux-arm-kernel@lists.infradead.org Signed-off-by: Stephen Boyd sboyd@kernel.org
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?