Lines Matching +full:boot +full:- +full:method

1 .. SPDX-License-Identifier: GPL-2.0
4 RISC-V Kernel Boot Requirements and Constraints
10 This document describes what the RISC-V kernel expects from bootloaders and
12 touching the early boot process. For the purposes of this document, the
13 ``early boot process`` refers to any code that runs before the final virtual
16 Pre-kernel Requirements and Constraints
19 The RISC-V kernel expects the following of bootloaders and platform firmware:
22 --------------
24 The RISC-V kernel expects:
30 ---------
32 The RISC-V kernel expects:
37 -------------------------------------
39 The RISC-V kernel must not map any resident memory, or memory protected with
44 ---------------
46 The RISC-V kernel expects to be placed at a PMD boundary (2MB aligned for rv64
51 --------------------
53 The firmware can pass either a devicetree or ACPI tables to the RISC-V kernel.
64 ------------
68 - ``RISCV_BOOT_SPINWAIT``: the firmware releases all harts in the kernel, one hart
69 wins a lottery and executes the early boot code while the other harts are
70 parked waiting for the initialization to finish. This method is mostly used to
71 support older firmwares without SBI HSM extension and M-mode RISC-V kernel.
72 - ``Ordered booting``: the firmware releases only one hart that will execute the
74 extension. The ordered booting method is the preferred booting method for
75 booting the RISC-V kernel because it can support CPU hotplug and kexec.
78 ----
83 When booting with UEFI, the RISC-V kernel will use only the EFI memory map to
86 The UEFI firmware must parse the subnodes of the ``/reserved-memory`` devicetree
88 those subnodes (``no-map`` and ``reusable``) into their correct EFI equivalent
89 (refer to section "3.5.4 /reserved-memory and UEFI" of the devicetree
90 specification v0.4-rc1).
95 When booting with UEFI, the EFI stub requires the boot hartid in order to pass
96 it to the RISC-V kernel in ``$a1``. The EFI stub retrieves the boot hartid using
99 - ``RISCV_EFI_BOOT_PROTOCOL`` (**preferred**).
100 - ``boot-hartid`` devicetree subnode (**deprecated**).
105 Early Boot Requirements and Constraints
108 The RISC-V kernel's early boot process operates under the following constraints:
111 -----------------------
118 ----------------------------
120 The installation of the virtual mapping is done in 2 steps in the RISC-V kernel:
143 -----------------------------
147 ``setup_vm_final()``, the RISC-V kernel uses the fixmap region to map the
151 Pre-MMU execution
152 -----------------
159 - ``-fno-pie``: This is needed for relocatable kernels which use ``-fPIE``,
162 - ``-mcmodel=medany``: Any access to a global symbol must be PC-relative to
164 - *all* instrumentation must also be disabled (that includes KASAN, ftrace and