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Date:   Sat, 02 May 2020 12:13:19 +0800
From:   Jiaxun Yang <jiaxun.yang@flygoat.com>
To:     Tiezhu Yang <yangtiezhu@loongson.cn>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>
CC:     linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
        Xuefeng Li <lixuefeng@loongson.cn>,
        Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Subject: Re: [PATCH v2] MIPS: tools: Show result for loongson3-llsc-check
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=E4=BA=8E 2020=E5=B9=B45=E6=9C=882=E6=97=A5 GMT+08:00 =E4=B8=8A=E5=8D=8811=
:55:01, Tiezhu Yang <yangtiezhu@loongson=2Ecn> =E5=86=99=E5=88=B0:
>It is better to show the result before loongson3-llsc-check exit,
>otherwise we can see nothing if the return status is EXIT_SUCCESS,
>it seems confusing=2E
>
>E=2Eg=2E without this patch:
>
>[loongson@localhost tools]$ =2E/loongson3-llsc-check =2E=2E/=2E=2E/=2E=2E=
/vmlinux
>[loongson@localhost tools]$
>
>With this patch:
>
>[loongson@localhost tools]$ =2E/loongson3-llsc-check =2E=2E/=2E=2E/=2E=2E=
/vmlinux
>loongson3-llsc-check returns success
>[loongson@localhost tools]$
>
>Signed-off-by: Tiezhu Yang <yangtiezhu@loongson=2Ecn>

Reviewed-by: Jiaxun Yang <jiaxun=2Eyang@flygoat=2Ecom>

Btw,
Just learned from Loongson that the latest generation of Loongson-3
doesn't have LLSC errata, also for Loongson 3A R2/R3, use synci instead
of sync would give better performance=2E

For performance approach, we'd better develop a method
to enable/disable these workarounds at runtime, looks like smp_alternative=
[1]
that was already employed by x86 and arm64 can be ported to MIPS and
serves to this target=2E

I'm struggling with device drivers recently so wish somebody
can take a look at it=2E

Thanks=2E

[1]: https://lwn=2Enet/Articles/164121/

>---
>
>v2:
>  - move "returns" after "loongson3-llsc-check" suggested by Sergei
>
> arch/mips/tools/loongson3-llsc-check=2Ec | 2 ++
> 1 file changed, 2 insertions(+)
>
>diff --git a/arch/mips/tools/loongson3-llsc-check=2Ec b/arch/mips/tools/l=
oongson3-llsc-check=2Ec
>index 0ebddd0=2E=2Ebdbc7b4 100644
>--- a/arch/mips/tools/loongson3-llsc-check=2Ec
>+++ b/arch/mips/tools/loongson3-llsc-check=2Ec
>@@ -303,5 +303,7 @@ int main(int argc, char *argv[])
> out_close:
> 	close(vmlinux_fd);
> out_ret:
>+	fprintf(stdout, "loongson3-llsc-check returns %s\n",
>+		status ? "failure" : "success");
> 	return status;
> }

--=20
Jiaxun Yang