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From: fengchengwen <fengchengwen@huawei.com>
To: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>,
	"thomas@monjalon.net" <thomas@monjalon.net>,
	"ferruh.yigit@intel.com" <ferruh.yigit@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
	"jerinj@marvell.com" <jerinj@marvell.com>,
	 Ruifeng Wang <Ruifeng.Wang@arm.com>,
	"viktorin@rehivetech.com" <viktorin@rehivetech.com>,
	"bruce.richardson@intel.com" <bruce.richardson@intel.com>,
	nd <nd@arm.com>
Subject: Re: [dpdk-dev] [PATCH 2/2] net/hns3: refactor SVE code compile method
Date: Thu, 13 May 2021 08:51:52 +0800	[thread overview]
Message-ID: <c3f5058b-9c5b-a394-82e6-7cd196ba4496@huawei.com> (raw)
In-Reply-To: <DBAPR08MB5814C0895FA61F0FE1B8705298529@DBAPR08MB5814.eurprd08.prod.outlook.com>



On 2021/5/13 7:21, Honnappa Nagarahalli wrote:
> <snip>
> 
>>
>>>
>>> Currently, the SVE code is compiled only when -march supports SVE
>>> (e.g. '- march=armv8.2a+sve'), there maybe some problem[1] with this
>> approach.
>>>
>>> The solution:
>>> a. If the minimum instruction set support SVE then compiles it.
>>> b. Else if the compiler support SVE then compiles it.
>>> c. Otherwise don't compile it.
>>>
>>> [1] https://mails.dpdk.org/archives/dev/2021-April/208189.html
>>>
>>> Fixes: 8c25b02b082a ("net/hns3: fix enabling SVE Rx/Tx")
>>> Fixes: 952ebacce4f2 ("net/hns3: support SVE Rx")
>>> Cc: stable@dpdk.org
>>>
>>> Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
>>> ---
>>>  drivers/net/hns3/hns3_rxtx.c |  2 +-
>>>  drivers/net/hns3/meson.build | 13 +++++++++++++
>>>  2 files changed, 14 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/net/hns3/hns3_rxtx.c
>>> b/drivers/net/hns3/hns3_rxtx.c index
>>> 1d7a769..4ef20c6 100644
>>> --- a/drivers/net/hns3/hns3_rxtx.c
>>> +++ b/drivers/net/hns3/hns3_rxtx.c
>>> @@ -2808,7 +2808,7 @@ hns3_get_default_vec_support(void)
>>>  static bool
>>>  hns3_get_sve_support(void)
>>>  {
>>> -#if defined(RTE_ARCH_ARM64) && defined(__ARM_FEATURE_SVE)
>>> +#if defined(CC_SVE_SUPPORT)
>>>  	if (rte_vect_get_max_simd_bitwidth() < RTE_VECT_SIMD_256)
>>>  		return false;
>>>  	if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_SVE))
>>> diff --git a/drivers/net/hns3/meson.build
>>> b/drivers/net/hns3/meson.build index
>>> 53c7df7..8563d70 100644
>>> --- a/drivers/net/hns3/meson.build
>>> +++ b/drivers/net/hns3/meson.build
>>> @@ -35,7 +35,20 @@ deps += ['hash']
>>>
>>>  if arch_subdir == 'arm' and dpdk_conf.get('RTE_ARCH_64')
>>>      sources += files('hns3_rxtx_vec.c')
>>> +
>>> +    # compile SVE when:
>>> +    # a. support SVE in minimum instruction set baseline
>>> +    # b. it's not minimum instruction set, but compiler support
>>>      if cc.get_define('__ARM_FEATURE_SVE', args: machine_args) != ''
>>> +        cflags += ['-DCC_SVE_SUPPORT']
>> Why is the CC_SVE_SUPPORT flag needed? The compiler has
>> __ARM_FEATURE_SVE flag already which gets defined when '+sve" is added to
>> '-march'.
>>

The CC_SVE_SUPPORT is used to implement the hns3_get_sve_support API (below),
this API located in another file which is hns3_rxtx.c, and this file was
compiled with default machine_args.

	static bool
	hns3_get_sve_support(void)
	{
	#if defined(CC_SVE_SUPPORT)
		if (rte_vect_get_max_simd_bitwidth() < RTE_VECT_SIMD_256)
			return false;
		if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_SVE))
			return true;
	#endif
		return false;
	}

If the machine_args doesn't support SVE but compiler support, we will compile
SVE code too, so in this case we need define CC_SVE_SUPPORT, so that in runtime
we could try judge whether support SVE. In this case, __ARM_FEATURE_SVE was not
defined because it is in hns3_rxtx.c which use default machine_args.

If the machine_args supports SVE we sure compile SVE code, in this case, to
maintain consistency, we also define this macro.

>>>          sources += files('hns3_rxtx_vec_sve.c')
>>> +    elif cc.has_argument('-march=armv8.2-a+sve')
>> I think this check and the above check do the same thing. i.e. both of them
>> check if +sve flag is passed to the compiler.
>>

Yes it is.

>>> +        cflags += ['-DCC_SVE_SUPPORT']
>>> +        hns3_sve_lib = static_library('hns3_sve_lib',
>>> +                        'hns3_rxtx_vec_sve.c',
>>> +                        dependencies: [static_rte_ethdev],
>>> +                        include_directories: includes,
>>> +                        c_args: [cflags, '-march=armv8.2-a+sve'])
>>> +        objs += hns3_sve_lib.extract_objects('hns3_rxtx_vec_sve.c')
> I do not understand the need of this block of code, appreciate if you could explain why this is required.
> 

This is typical usage for compiling some soure file with custom flags (here is '-march=armv8.2-a+sve')
Please ref [1] with keyword 'extract_objects'

[1] https://mesonbuild.com/Reference-manual.html

>>>      endif
>>>  endif
>>> --
>>> 2.8.1
> 
> 
> .
> 


  reply	other threads:[~2021-05-13  0:51 UTC|newest]

Thread overview: 80+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-12  8:28 [dpdk-dev] [PATCH 0/2] bugfix for Kunpeng930 SVE compile Chengwen Feng
2021-05-12  8:28 ` [dpdk-dev] [PATCH 1/2] config/arm: add non-SVE march for soc kunpeng930 Chengwen Feng
2021-05-12  8:44   ` Jerin Jacob
2021-05-12 23:00     ` Honnappa Nagarahalli
2021-05-13  4:49       ` fengchengwen
2021-05-12  8:28 ` [dpdk-dev] [PATCH 2/2] net/hns3: refactor SVE code compile method Chengwen Feng
2021-05-12 23:12   ` Honnappa Nagarahalli
2021-05-12 23:21     ` Honnappa Nagarahalli
2021-05-13  0:51       ` fengchengwen [this message]
2021-05-13 20:42         ` Honnappa Nagarahalli
2021-05-13 10:04     ` Bruce Richardson
2021-05-13  4:41 ` [dpdk-dev] [PATCH v2 0/2] bugfix for Kunpeng SVE compile Chengwen Feng
2021-05-13  4:41   ` [dpdk-dev] [PATCH v2 1/2] config/arm: select best -march parameter for kunpeng soc Chengwen Feng
2021-05-13  4:41   ` [dpdk-dev] [PATCH v2 2/2] net/hns3: refactor SVE code compile method Chengwen Feng
2021-05-13  6:16 ` [dpdk-dev] [PATCH v3 0/2] bugfix for Kunpeng SVE compile Chengwen Feng
2021-05-13  6:16   ` [dpdk-dev] [PATCH v3 1/2] config/arm: select most suitable -march for kunpeng soc Chengwen Feng
2021-05-13  6:16   ` [dpdk-dev] [PATCH v3 2/2] net/hns3: refactor SVE code compile method Chengwen Feng
2021-05-13 13:08 ` [dpdk-dev] [PATCH v4 0/2] bugfix for Kunpeng SVE compile Chengwen Feng
2021-05-13 13:08   ` [dpdk-dev] [PATCH v4 1/2] config/arm: select most suitable -march for kunpeng soc Chengwen Feng
2021-05-13 15:24     ` Jerin Jacob
2021-05-13 23:12       ` Honnappa Nagarahalli
2021-05-14 10:23         ` fengchengwen
2021-05-18 13:25           ` Honnappa Nagarahalli
2021-05-18 13:45             ` Jerin Jacob
2021-05-13 13:08   ` [dpdk-dev] [PATCH v4 2/2] net/hns3: refactor SVE code compile method Chengwen Feng
2021-05-13 22:19     ` Honnappa Nagarahalli
2021-05-14  2:53       ` fengchengwen
2021-05-14  9:53 ` [dpdk-dev] [PATCH v5 0/2] bugfix for Kunpeng SVE compile Chengwen Feng
2021-05-14  9:53   ` [dpdk-dev] [PATCH v5 1/2] config/arm: select most suitable -march for kunpeng soc Chengwen Feng
2021-05-14  9:53   ` [dpdk-dev] [PATCH v5 2/2] net/hns3: refactor SVE code compile method Chengwen Feng
2021-05-14 14:12     ` Honnappa Nagarahalli
2021-05-18 12:41       ` fengchengwen
2021-05-18 13:11         ` Honnappa Nagarahalli
2021-05-18 13:12           ` Honnappa Nagarahalli
2021-05-18 13:24         ` Ferruh Yigit
2021-05-18 16:27       ` Ferruh Yigit
2021-05-19  0:23         ` fengchengwen
2021-05-19  8:08         ` David Marchand
2021-05-19  9:27           ` Ferruh Yigit
2021-05-19 12:16             ` fengchengwen
2021-05-19 12:37               ` David Marchand
2021-05-19 13:35                 ` fengchengwen
2021-05-18 14:40     ` Ferruh Yigit
2021-05-18 15:15       ` Bruce Richardson
2021-05-18 16:12         ` Ferruh Yigit
2021-05-18 15:48       ` Honnappa Nagarahalli
2021-05-18 16:00         ` Ferruh Yigit
2021-05-18 16:12           ` Honnappa Nagarahalli
2021-05-18 16:37             ` Ferruh Yigit
2021-05-19  0:18               ` fengchengwen
2021-05-19 13:25 ` [dpdk-dev] [PATCH v6 0/2] bugfix for Kunpeng SVE compile Chengwen Feng
2021-05-19 13:25   ` [dpdk-dev] [PATCH v6 1/2] config/arm: select most suitable -march for kunpeng soc Chengwen Feng
2021-05-19 14:05     ` Jerin Jacob
2021-05-20 22:38       ` Honnappa Nagarahalli
2021-05-19 13:25   ` [dpdk-dev] [PATCH v6 2/2] net/hns3: refactor SVE code compile method Chengwen Feng
2021-05-19 15:02     ` Ferruh Yigit
2021-05-20  1:11       ` fengchengwen
2021-05-20  7:57         ` Ferruh Yigit
2021-05-20  8:24     ` Ruifeng Wang
2021-05-20 10:55       ` fengchengwen
2021-05-21  5:21         ` Ruifeng Wang
2021-05-21  6:53           ` fengchengwen
2021-05-24  5:38             ` Ruifeng Wang
2021-05-24  8:43               ` fengchengwen
2021-05-24 10:03                 ` Ruifeng Wang
2021-05-24 13:15                   ` fengchengwen
2021-05-24 13:12 ` [dpdk-dev] [PATCH v7 0/2] bugfix for Kunpeng SVE compile Chengwen Feng
2021-05-24 13:12   ` [dpdk-dev] [PATCH v7 1/2] config/arm: select most suitable -march for kunpeng soc Chengwen Feng
2021-05-24 13:12   ` [dpdk-dev] [PATCH v7 2/2] net/hns3: refactor SVE code compile method Chengwen Feng
2021-05-24 13:23 ` [dpdk-dev] [PATCH v8 0/2] bugfix for Kunpeng SVE compile Chengwen Feng
2021-05-24 13:23   ` [dpdk-dev] [PATCH v8 1/2] config/arm: select most suitable -march for kunpeng soc Chengwen Feng
2021-06-17  7:03     ` Thomas Monjalon
2021-06-17 23:33       ` Honnappa Nagarahalli
2021-06-21  0:52         ` fengchengwen
2021-06-23  8:08           ` Thomas Monjalon
2021-06-23  8:24             ` fengchengwen
2021-05-24 13:23   ` [dpdk-dev] [PATCH v8 2/2] net/hns3: refactor SVE code compile method Chengwen Feng
2021-05-25  6:04     ` Ruifeng Wang
2021-05-27  7:07       ` Fengchengwen
2021-06-12  7:09       ` fengchengwen

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