[PATCH 00/12] Some improvements on boot sequence

[Anup Patel]

On Wed, Jun 11, 2025 at 5:42 PM Xiang W <wxjstz at 126.com> wrote:
>
> This series of patches mainly merges init_coldboot and init_warm_startup,

The existing code of having clearly separate coldboot, warm_startup, and
warm_resume paths are straightforward to understand and maintain. Even,
Linux has separate start_kernel() (for boot/primary HART), smp_callin()
(for non-boot/secondary HARTs) and __cpu_resume_enter() (for HART
resume).

> and separates sbi_hsm_hart_wait from sbi_hsm_init, so that non-coldboot
> HART can perform more initialization tasks before entering HSM wait. In
> order to improve some multi HARTs related codes.

Performing more initialization on non-coldboot HART before
sbi_hsm_hart_wait() is redundant because non-coldboot HART
will have to anyway wait until coldboot HART uses SBI HSM
start call.

On the contrary, doing sbi_hsm_hart_wait() as the first thing for
non-coldboot HART ensures that HART is fully initialized only
after coldboot HART decides to bring it up (via SBI HSM start)
which also enables us to poweroff non-coldboot HART on
platforms with full hart-hotplug.

>
> Xiang W (12):
>   lib: sbi: Add coldboot parameters to some initialization functions
>   lib: sbi: Optimise the boot sequence
>   lib: sbi: Implement synchronisation and wait between multiple HARTs
>   lib: sbi: Remove wait_for_coldboot and wake_coldboot_harts
>   lib: sbi: Add wait operations in some initialization functions
>   lib/utils: Make fdt_parse_isa_extensions reentrant
>   lib: sbi: Initialize as much as possible before sbi_hsm_init
>   lib: sbi: Remove cold_boot from sbi_hsm_init
>   lib: sbi: Ensure that all Harts complete sbi_hart_init
>   lib/utils: Fix Zicntr detection in fdt_cpu_fixup
>   lib: sbi: Fix dtbr initialization
>   lib: sbi: Remove cold_boot from sbi_double_trap_init

This all seems unnecessary churn and I still find it hard
to understand the underlying problem.

>
>  include/sbi/sbi_domain.h   |   2 +-
>  include/sbi/sbi_hart.h     |   6 +
>  include/sbi/sbi_hsm.h      |   5 +-
>  include/sbi/sbi_mpxy.h     |   2 +-
>  lib/sbi/sbi_dbtr.c         |  32 +++-
>  lib/sbi/sbi_domain.c       |   9 +-
>  lib/sbi/sbi_double_trap.c  |   7 +-
>  lib/sbi/sbi_ecall_dbtr.c   |   2 +-
>  lib/sbi/sbi_fwft.c         |   3 +
>  lib/sbi/sbi_hart.c         |  77 +++++++++-
>  lib/sbi/sbi_hsm.c          |  51 +++----
>  lib/sbi/sbi_init.c         | 306 +++++++++++++------------------------
>  lib/sbi/sbi_ipi.c          |   3 +
>  lib/sbi/sbi_irqchip.c      |   5 +-
>  lib/sbi/sbi_mpxy.c         |   4 +-
>  lib/sbi/sbi_pmu.c          |   3 +
>  lib/sbi/sbi_sse.c          |   3 +
>  lib/sbi/sbi_timer.c        |   3 +
>  lib/sbi/sbi_tlb.c          |   3 +
>  lib/utils/fdt/fdt_fixup.c  |  24 +--
>  lib/utils/fdt/fdt_helper.c |   4 +
>  21 files changed, 300 insertions(+), 254 deletions(-)
>
> --
> 2.47.2
>

Regards,
Anup