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Re: [Qemu-devel] [PATCH] atomic failures on qemu-system-riscv64
From: |
Palmer Dabbelt |
Subject: |
Re: [Qemu-devel] [PATCH] atomic failures on qemu-system-riscv64 |
Date: |
Sun, 23 Jun 2019 23:42:42 -0700 |
On Mon, Jun 17, 2019 at 4:53 PM Richard Henderson <
address@hidden> wrote:
> On 6/16/19 12:19 PM, Joel Sing wrote:
> > + /*
> > + * Clear the load reservation, since an SC must fail if there is
> > + * an SC to any address, in between an LR and SC pair.
> > + */
> > + tcg_gen_movi_tl(load_res, 0);
> > +
> > gen_set_label(l2);
>
> This clear needs to be moved down below label l2.
> Otherwise, with lr / sc / sc, the second sc could succeed in error.
>
> FWIW, other targets have used -1 as the "invalid" load reservation, since
> the
> architecture does not require address 0 to be unmapped. This should be
> quite
> visible in M-mode with paging disabled and ram at offset 0. Often, other
> targets require alignment for the lr/sc address, though I don't see that
> for riscv.
>
>
> r~
>
Joel: can you submit this with a "Signed-off-by" line? There's only a week
until the soft freeze, and I'd really like this in if possible. It'd be
great if you could fix up the other issues, but I can't even do that myself
without a SOB.
- [Qemu-devel] [PATCH] atomic failures on qemu-system-riscv64, Joel Sing, 2019/06/16
- Re: [Qemu-devel] [PATCH] atomic failures on qemu-system-riscv64, no-reply, 2019/06/16
- Re: [Qemu-devel] [PATCH] atomic failures on qemu-system-riscv64, Richard Henderson, 2019/06/17
- Re: [Qemu-devel] [PATCH] atomic failures on qemu-system-riscv64,
Palmer Dabbelt <=
- Re: [Qemu-devel] [PATCH] atomic failures on qemu-system-riscv64, Joel Sing, 2019/06/24
- Re: [Qemu-devel] [PATCH] atomic failures on qemu-system-riscv64, Richard Henderson, 2019/06/25
- Re: [Qemu-devel] [PATCH] atomic failures on qemu-system-riscv64, Palmer Dabbelt, 2019/06/26
- Re: [Qemu-devel] [PATCH] atomic failures on qemu-system-riscv64, Richard Henderson, 2019/06/26
- Re: [Qemu-devel] [PATCH] atomic failures on qemu-system-riscv64, Palmer Dabbelt, 2019/06/26
- Re: [Qemu-devel] [PATCH] atomic failures on qemu-system-riscv64, Richard Henderson, 2019/06/26
- Re: [Qemu-devel] [PATCH] atomic failures on qemu-system-riscv64, Palmer Dabbelt, 2019/06/26
- Re: [Qemu-devel] [PATCH] atomic failures on qemu-system-riscv64, Richard Henderson, 2019/06/25
- Re: [Qemu-devel] [PATCH] atomic failures on qemu-system-riscv64, Palmer Dabbelt, 2019/06/26