From: Vineet Gupta <Vineet.Gupta1@synopsys.com>
To: Alexey Brodkin <Alexey.Brodkin@synopsys.com>,
Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Cc: "linux-snps-arc@lists.infradead.org"
<linux-snps-arc@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 1/4] ARC: allow to override default mcpu compiler flag
Date: Tue, 16 Jun 2020 22:12:27 +0000 [thread overview]
Message-ID: <f3f54ba2-c050-83a2-ea93-dc147fd4bcfe@synopsys.com> (raw)
In-Reply-To: <MWHPR1201MB0046338E4B38598FFB5DBCB9A1860@MWHPR1201MB0046.namprd12.prod.outlook.com>
On 6/5/20 3:47 AM, Alexey Brodkin wrote:
> Hi Eugeniy,
>
> A couple of minor notes below.
>
>> -----Original Message-----
>> From: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
>> Sent: Thursday, June 4, 2020 8:39 PM
>> To: linux-snps-arc@lists.infradead.org; Vineet Gupta <vgupta@synopsys.com>
>> Cc: linux-kernel@vger.kernel.org; Alexey Brodkin <abrodkin@synopsys.com>; Eugeniy Paltsev
>> <paltsev@synopsys.com>
>> Subject: [PATCH v2 1/4] ARC: allow to override default mcpu compiler flag
>>
>> Kernel builds set their own default -mcpu for a given ISA build.
>
> We used to use a default "-mcpu" per ARC ISA version (one for ARCompact
> and one for ARCv2).
>
>> But that gets in the way of "custom" -mcpu flags from propagating
>> into kernel build.
>
> But with more versions of CPUs & SoCs becoming available we want to
> be able to fine-tune generated code more precise.
>
>> This will also be used in next patches for HSDK-4xD board support which
>> uses a different -mcpu to effect dual issue scheduling.
>
> "...for utilization of the new CPU's dual-issue capabilities"?
>
>> +++ b/arch/arc/Makefile
>> @@ -10,8 +10,25 @@ CROSS_COMPILE := $(call cc-cross-prefix, arc-linux- arceb-linux-)
>> endif
>>
>> cflags-y += -fno-common -pipe -fno-builtin -mmedium-calls -D__linux__
>> -cflags-$(CONFIG_ISA_ARCOMPACT) += -mA7
>> -cflags-$(CONFIG_ISA_ARCV2) += -mcpu=hs38
>> +
>> +tune-mcpu-def-$(CONFIG_ISA_ARCOMPACT) := -mA7
>
> I'd suggest to either swap "-mA7" which is being obsoleted with "-mcpu=arc700"
> right here or as a separate change, otherwise we may soon get ATC700 builds
> broken with newer compilers.
FWIW I've added a modified variant of this patch to for-curr as we need it for
ongoing ARC64 port as well.
-Vineet
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next prev parent reply other threads:[~2020-06-16 22:12 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-04 17:39 [PATCH v2 0/4] ARC: [plat-hsdk-4xd] initial port for HSDK-4xD board Eugeniy Paltsev
2020-06-04 17:39 ` [PATCH v2 1/4] ARC: allow to override default mcpu compiler flag Eugeniy Paltsev
2020-06-04 18:27 ` Vineet Gupta
2020-06-05 10:47 ` Alexey Brodkin
2020-06-16 22:12 ` Vineet Gupta [this message]
2020-06-04 17:39 ` [PATCH v2 2/4] ARC: ARCv2: support loop buffer (LPB) disabling Eugeniy Paltsev
2020-06-18 19:50 ` Eugeniy Paltsev
2020-06-18 20:00 ` Vineet Gupta
2020-06-04 17:39 ` [PATCH v2 3/4] ARC: [plat-hsdk-4xd] initial port for HSDK-4xD board Eugeniy Paltsev
2020-06-04 22:02 ` Rob Herring
2020-06-04 17:39 ` [PATCH v2 4/4] ARC: [plat-hsdk*] document HSDK-4xD board/SoC bindings Eugeniy Paltsev
2020-06-04 20:00 ` [PATCH v2 0/4] ARC: [plat-hsdk-4xd] initial port for HSDK-4xD board Vineet Gupta
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