[PATCH] lib: sbi: Drop fw_rw_offset alignment requirement for single fw region

[Anup Patel]

On Sat, May 23, 2026 at 4:57 AM Anirudh Srinivasan
<asrinivasan at oss.tenstorrent.com> wrote:
>
> From: Nicholas Piggin <npiggin at gmail.com>
>
> In a single fw region scheme, there is no separate PMP created for RW
> memory. The checks that opensbi does for the alignment between fw_start
> and fw_rw_start (using fw_rw_offset) and the power of 2 check for
> fw_rw_offset are no longer necessary.
>
> Update sbi_domain_init so that these checks are only done in the non
> single fw region scheme.
>
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> Co-developed-by: Anirudh Srinivasan <asrinivasan at oss.tenstorrent.com>
> Signed-off-by: Anirudh Srinivasan <asrinivasan at oss.tenstorrent.com>

LGTM.

Reviewed-by: Anup Patel <anup at brainfault.org>

Applied this patch to the riscv/opensbi repo.

Thanks,
Anup

> ---
>  lib/sbi/sbi_domain.c | 27 +++++++++++++++------------
>  1 file changed, 15 insertions(+), 12 deletions(-)
>
> diff --git a/lib/sbi/sbi_domain.c b/lib/sbi/sbi_domain.c
> index 4f458ac0..296ee81b 100644
> --- a/lib/sbi/sbi_domain.c
> +++ b/lib/sbi/sbi_domain.c
> @@ -871,20 +871,23 @@ int sbi_domain_init(struct sbi_scratch *scratch, u32 cold_hartid)
>         struct sbi_hartmask *root_hmask;
>         struct sbi_domain_memregion *root_memregs;
>         int root_memregs_count = 0;
> +       const struct sbi_platform *plat = sbi_platform_ptr(scratch);
> +       bool fw_single_region = sbi_platform_single_fw_region(plat);
>
>         SBI_INIT_LIST_HEAD(&domain_list);
>
> -       if (scratch->fw_rw_offset == 0 ||
> -           (scratch->fw_rw_offset & (scratch->fw_rw_offset - 1)) != 0) {
> -               sbi_printf("%s: fw_rw_offset is not a power of 2 (0x%lx)\n",
> -                          __func__, scratch->fw_rw_offset);
> -               return SBI_EINVAL;
> -       }
> -
> -       if ((scratch->fw_start & (scratch->fw_rw_offset - 1)) != 0) {
> -               sbi_printf("%s: fw_start and fw_rw_offset not aligned\n",
> -                          __func__);
> -               return SBI_EINVAL;
> +       if (!fw_single_region) {
> +               if (scratch->fw_rw_offset == 0 ||
> +                   (scratch->fw_rw_offset & (scratch->fw_rw_offset - 1)) != 0) {
> +                       sbi_printf("%s: fw_rw_offset is not a power of 2 (0x%lx)\n",
> +                                  __func__, scratch->fw_rw_offset);
> +                       return SBI_EINVAL;
> +               }
> +               if ((scratch->fw_start & (scratch->fw_rw_offset - 1)) != 0) {
> +                       sbi_printf("%s: fw_start and fw_rw_offset not aligned\n",
> +                                  __func__);
> +                       return SBI_EINVAL;
> +               }
>         }
>
>         domain_hart_ptr_offset = sbi_scratch_alloc_type_offset(void *);
> @@ -913,7 +916,7 @@ int sbi_domain_init(struct sbi_scratch *scratch, u32 cold_hartid)
>         root.possible_harts = root_hmask;
>
>         /* Root domain firmware memory region */
> -       if (sbi_platform_single_fw_region(sbi_platform_ptr(scratch))) {
> +       if (fw_single_region) {
>                 sbi_domain_memregion_init(scratch->fw_start, scratch->fw_size,
>                                           (SBI_DOMAIN_MEMREGION_M_READABLE |
>                                            SBI_DOMAIN_MEMREGION_M_WRITABLE |
>
> ---
> base-commit: e7fa66c2160ec139de1853a00f669c09320a9256
> change-id: 20260522-fw_rw_start_alignment-44eaac884823
>
> Best regards,
> --
> Anirudh Srinivasan <asrinivasan at oss.tenstorrent.com>
>
>
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