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    SubjectRe: [PATCH -fixes v2 3/3] riscv: No need to relocate the dtb as it lies in the fixmap region
    On Wed, Mar 29, 2023 at 10:19:32AM +0200, Alexandre Ghiti wrote:
    > We used to access the dtb via its linear mapping address but now that the
    > dtb early mapping was moved in the fixmap region, we can keep using this
    > address since it is present in swapper_pg_dir, and remove the dtb
    > relocation.
    >
    > Note that the relocation was wrong anyway since early_memremap() is
    > restricted to 256K whereas the maximum fdt size is 2MB.

    So, should this be marked as a fix, and backported along with 1/3?
    Either way,
    Reviewed-by: Conor Dooley <conor.dooley@microchip.com>

    And from v1 (although I didn't actually send it for idk what reason):
    Tested-by: Conor Dooley <conor.dooley@microchip.com>

    Thanks,
    Conor.

    >
    > Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
    > ---
    > arch/riscv/mm/init.c | 21 ++-------------------
    > 1 file changed, 2 insertions(+), 19 deletions(-)
    >
    > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
    > index fb78d6bbabae..0f14f4a8d179 100644
    > --- a/arch/riscv/mm/init.c
    > +++ b/arch/riscv/mm/init.c
    > @@ -249,25 +249,8 @@ static void __init setup_bootmem(void)
    > * early_init_fdt_reserve_self() since __pa() does
    > * not work for DTB pointers that are fixmap addresses
    > */
    > - if (!IS_ENABLED(CONFIG_BUILTIN_DTB)) {
    > - /*
    > - * In case the DTB is not located in a memory region we won't
    > - * be able to locate it later on via the linear mapping and
    > - * get a segfault when accessing it via __va(dtb_early_pa).
    > - * To avoid this situation copy DTB to a memory region.
    > - * Note that memblock_phys_alloc will also reserve DTB region.
    > - */
    > - if (!memblock_is_memory(dtb_early_pa)) {
    > - size_t fdt_size = fdt_totalsize(dtb_early_va);
    > - phys_addr_t new_dtb_early_pa = memblock_phys_alloc(fdt_size, PAGE_SIZE);
    > - void *new_dtb_early_va = early_memremap(new_dtb_early_pa, fdt_size);
    > -
    > - memcpy(new_dtb_early_va, dtb_early_va, fdt_size);
    > - early_memunmap(new_dtb_early_va, fdt_size);
    > - _dtb_early_pa = new_dtb_early_pa;
    > - } else
    > - memblock_reserve(dtb_early_pa, fdt_totalsize(dtb_early_va));
    > - }
    > + if (!IS_ENABLED(CONFIG_BUILTIN_DTB))
    > + memblock_reserve(dtb_early_pa, fdt_totalsize(dtb_early_va));
    >
    > dma_contiguous_reserve(dma32_phys_limit);
    > if (IS_ENABLED(CONFIG_64BIT))
    > --
    > 2.37.2
    >
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