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SubjectRe: [PATCH v2] riscv: keep 32-bit kernel to 32-bit phys_addr_t
On Mon, 06 Jan 2020 15:20:24 PST (-0800), Olof Johansson wrote:
> While rv32 technically has 34-bit physical addresses, no current platforms
> use it and it's likely to shake out driver bugs.
>
> Let's keep 64-bit phys_addr_t off on 32-bit builds until one shows up,
> since other work will be needed to make such a system useful anyway.
>
> PHYS_ADDR_T_64BIT is def_bool 64BIT, so just remove the select.
>
> Signed-off-by: Olof Johansson <olof@lixom.net>
> ---
>
> v2: Just remove the select, since it's set by default if CONFIG_64BIT
>
> arch/riscv/Kconfig | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index a31169b02ec06..569fc6deb94d6 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -12,8 +12,6 @@ config 32BIT
>
> config RISCV
> def_bool y
> - # even on 32-bit, physical (and DMA) addresses are > 32-bits
> - select PHYS_ADDR_T_64BIT
> select OF
> select OF_EARLY_FLATTREE
> select OF_IRQ

I gave 5.5-rc5 a quick test on a 32-bit QEMU with 8GiB of RAM and the system
wouldn't boot, so we've got at least some bugs floating around somewhere.
Given that this doesn't work I don't see any reason to keep it around as an
option, as if someone wants to make it work there's a lot more to do than make
things compile.

I've put this on for-next. If anyone cares about 34-bit physical addresses on
rv32 then now is the right time to speak up... ideally by fixing it :)

Thanks!

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