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From:   Bin Meng <bmeng.cn@gmail.com>
Date:   Thu, 17 Dec 2020 16:53:15 +0800
Message-ID: <CAEUhbmUXXH2P=jagTx88J86ec=C9eur9fkfGM=OdN7oqmD7W0g@mail.gmail.com>
Subject: Re: [PATCH] RISC-V: Fix usage of memblock_enforce_memory_limit
To:     Atish Patra <atishp@atishpatra.org>
Cc:     Atish Patra <atish.patra@wdc.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Anup Patel <anup.patel@wdc.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        Mike Rapoport <rppt@kernel.org>
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Hi Atish,

On Thu, Dec 17, 2020 at 4:43 PM Atish Patra <atishp@atishpatra.org> wrote:
>
> On Thu, Dec 17, 2020 at 12:12 AM Bin Meng <bmeng.cn@gmail.com> wrote:
> >
> > Hi Atish,
> >
> > On Thu, Dec 17, 2020 at 3:49 PM Atish Patra <atish.patra@wdc.com> wrote:
> > >
> > > memblock_enforce_memory_limit accepts the maximum memory size not the last
> > > address. Fix the function invocation correctly.
> > >
> > > Fixes: 1bd14a66ee52 ("RISC-V: Remove any memblock representing unusable memory area")
> > >
> > > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> > > ---
> > >  arch/riscv/mm/init.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> >
> > Thank you for working on this.
> >
> > Tested with QEMU 5.2.0 on 32-bit 'virt' and 'sifive_u', with
> > fw_jump.bin used as the -bios.
>
> fw_dynamic should also work unless you are using more than 1G of memory.
> Linux kernel can only support 1G of memory for RV32. The current

I have always been using -m 2G for testing both 32-bit and 64-bit.
32-bit 'virt' with 2G memory boots the 32-bit kernel fine.

$ qemu-system-riscv32 -nographic -M virt -m 2G -smp 4 -kernel
arch/riscv/boot/Image -bios fw_jump.bin

> Kconfig is bit misleading and
> I will send a patch to update the description.
>
> However, kernel should be able to ignore any memory beyond what it can
> address and continue.
> I will investigate more.
>
> > 32-bit 'virt' boots, but 32-bit 'sifive_u' still does not boot, which
> > should be another issue because reverting the original 1bd14a66ee52 it
> > still does not help 'sifive_u'.
> >
>
> Are you using more than 1G of memory ? Let me know if the kernel boots
> if you use 1G.

Kernel does not boot with 1G memory on 32-bit 'sifive_u', either with
fw_jump.bin or fw_dynamic.bin.

$ qemu-system-riscv32 -nographic -M sifive_u -m 1G -smp 5 -kernel
arch/riscv/boot/Image -bios fw_jump.bin

>
> > Tested-by: Bin Meng <bin.meng@windriver.com>
> >
> > I believe the following tag should also be added and patch cc'ed to
> > stable-kernel:
> >
> > Reported-by: Bin Meng <bin.meng@windriver.com>
> > Cc: <stable@vger.kernel.org> # 5.10

Regards,
Bin