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To: Panu Matilainen <pmatilai@redhat.com>,
 Thomas Monjalon <thomas.monjalon@6wind.com>
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From: =?UTF-8?Q?Simon_K=c3=a5gstr=c3=b6m?= <simon.kagstrom@netinsight.net>
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Date: Mon, 7 Dec 2015 12:47:19 +0100
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Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v2] mk: pass EXTRA_CFLAGS to AUTO_CPUFLAGS to
 enable local modifications
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On 2015-12-07 09:33, Panu Matilainen wrote:
> On 12/04/2015 08:53 PM, Thomas Monjalon wrote:
>>>>> We have encountered a CPU where the AES-NI instruction set is disabled
>>>>> due to export restrictions. Since the build machine and target machine
>>>>> is different, using -native configs doesn't work, and on this CPU, the
>>>>> application refuses to run due to the AES CPU flags being amiss.
>>>>>
>>>>> The patch passes EXTRA_CFLAGS to the figure-out-cpu-flags helper,
>>>>> which allows us to add -mno-aes to the compile flags and resolve this
>>>>> problem.
> 
> More specifically, when EXTRA_CFLAGS contains warning flag manipulation
> this patch can cause mismatch between other options that are okay
> elsewhere in dpdk make. A simple fix is to pass WERROR_FLAGS to
> AUTO_CPUFLAGS too to counter this, ie
> 
> diff --git a/mk/rte.cpuflags.mk b/mk/rte.cpuflags.mk
> index c6bb8de..28f203b 100644
> --- a/mk/rte.cpuflags.mk
> +++ b/mk/rte.cpuflags.mk
> @@ -33,7 +33,7 @@
>  # used to set the RTE_CPUFLAG_* environment variables giving details
>  # of what instruction sets the target cpu supports.
> 
> -AUTO_CPUFLAGS := $(shell $(CC) $(MACHINE_CFLAGS) $(EXTRA_CFLAGS) -dM -E
> - < /dev/null)
> +AUTO_CPUFLAGS := $(shell $(CC) $(MACHINE_CFLAGS) $(WERROR_FLAGS)
> $(EXTRA_CFLAGS) -dM -E - < /dev/null)

Looks fine to me at least.

// Simon