| Message ID | 20200224221949.28826-2-atish.patra@wdc.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Add boot hartid to a Device tree | expand |
On Mon, 24 Feb 2020 at 23:20, Atish Patra <atish.patra at wdc.com> wrote: > > Linux booting protocol mandates that register "a0" contains the hartid. > However, U-boot can not pass the hartid via a0 during EFI boot without > breaking the UEFI specification. > It is not about breaking or violating the UEFI specification. It is about the firmware using a conduit that is already being used to describe the hardware to the OS to pass an extra piece of information that the OS needs. > Add a DT node under chosen node to indicate the boot hartid. EFI stub > in Linux kernel will parse this node and pass it to the real kernel > in "a0" before jumping to it. > > Signed-off-by: Atish Patra <atish.patra at wdc.com> > --- > arch/riscv/lib/bootm.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/arch/riscv/lib/bootm.c b/arch/riscv/lib/bootm.c > index fad16901c5f2..b84cc2db2016 100644 > --- a/arch/riscv/lib/bootm.c > +++ b/arch/riscv/lib/bootm.c > @@ -28,6 +28,19 @@ __weak void board_quiesce_devices(void) > > int arch_fixup_fdt(void *blob) > { > + u32 size; > + int chosen_offset, err; > + > + size = fdt_totalsize(blob); > + err = fdt_open_into(blob, blob, size + 32); > + if (err < 0) { > + printf("Device Tree can't be expanded to accmodate new node"); 'accommodate' > + return -1; > + } > + chosen_offset = fdt_path_offset(blob, "/chosen"); > + fdt_setprop_u64(blob, chosen_offset, "efi-boot-hartid", I assume that boot hartid does not change value when you boot via UEFI, so this should simply be /chosen/boot-hartid > + gd->arch.boot_hart); > + > return 0; > } > > -- > 2.24.0 >
diff --git a/arch/riscv/lib/bootm.c b/arch/riscv/lib/bootm.c index fad16901c5f2..b84cc2db2016 100644 --- a/arch/riscv/lib/bootm.c +++ b/arch/riscv/lib/bootm.c @@ -28,6 +28,19 @@ __weak void board_quiesce_devices(void) int arch_fixup_fdt(void *blob) { + u32 size; + int chosen_offset, err; + + size = fdt_totalsize(blob); + err = fdt_open_into(blob, blob, size + 32); + if (err < 0) { + printf("Device Tree can't be expanded to accmodate new node"); + return -1; + } + chosen_offset = fdt_path_offset(blob, "/chosen"); + fdt_setprop_u64(blob, chosen_offset, "efi-boot-hartid", + gd->arch.boot_hart); + return 0; }
Linux booting protocol mandates that register "a0" contains the hartid. However, U-boot can not pass the hartid via a0 during EFI boot without breaking the UEFI specification. Add a DT node under chosen node to indicate the boot hartid. EFI stub in Linux kernel will parse this node and pass it to the real kernel in "a0" before jumping to it. Signed-off-by: Atish Patra <atish.patra at wdc.com> --- arch/riscv/lib/bootm.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)