-----Original Message-----
From: Jerin Jacob [mailto:jerin.jacob@caviumnetworks.com]
Sent: Wednesday, January 31, 2018 1:31 PM
To: Ophir Munk <redacted>
Cc: dev@dpdk.org; Thomas Monjalon <redacted>; Pascal
Mazon [off-list ref]; Jan Viktorin
[off-list ref]; Jianbo Liu [off-list ref]
Subject: Re: [dpdk-dev] [PATCH] net/tap: fix build issue with ARM32

-----Original Message-----

quoted

Date: Wed, 31 Jan 2018 10:38:32 +0000
From: Ophir Munk <redacted>
To: Jerin Jacob <redacted>
CC: "dev@dpdk.org" <redacted>, Thomas Monjalon
[off-list ref],  Pascal Mazon [off-list ref],

Jan

quoted

Viktorin  [off-list ref], Jianbo Liu [off-list ref]
Subject: RE: [dpdk-dev]  [PATCH] net/tap: fix build issue with ARM32

Hi,
Please see inline

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-----Original Message-----
From: Jerin Jacob [mailto:jerin.jacob@caviumnetworks.com]
Sent: Wednesday, January 31, 2018 12:24 PM
To: Ophir Munk <redacted>
Cc: dev@dpdk.org; Thomas Monjalon <redacted>; Pascal
Mazon [off-list ref]; Jan Viktorin
[off-list ref]; Jianbo Liu [off-list ref]
Subject: Re: [dpdk-dev] [PATCH] net/tap: fix build issue with ARM32

-----Original Message-----

quoted

Date: Wed, 31 Jan 2018 09:59:45 +0000
From: Ophir Munk <redacted>
To: Jerin Jacob <redacted>, "dev@dpdk.org"
 [off-list ref]
CC: Thomas Monjalon <redacted>, Pascal Mazon
[off-list ref], Jan Viktorin [off-list ref],
Jianbo  Liu [off-list ref]
Subject: RE: [dpdk-dev]  [PATCH] net/tap: fix build issue with
ARM32

Hi,
Please see comments inline

quoted

-----Original Message-----
From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Jerin Jacob
Sent: Wednesday, January 31, 2018 7:14 AM
To: dev@dpdk.org
Cc: Thomas Monjalon <redacted>; Jerin Jacob
[off-list ref]; Pascal Mazon
[off-list ref]; Jan Viktorin
[off-list ref]; Jianbo Liu [off-list ref]
Subject: [dpdk-dev] [PATCH] net/tap: fix build issue with ARM32

arm32 Linux does not support eBPF interface.
Since tap PMD driver has a dependency on eBPF(the symbol
__NR_bpf), disabling it armv7 config.

compilation error log:
In file included from /tmp/dpdk/drivers/net/tap/tap_bpf_api.c:15:0:
/tmp/dpdk/drivers/net/tap/tap_bpf.h:103:4: error: #error
__NR_bpf not defined  #  error __NR_bpf not defined
    ^

arm architecture is missing is file drivers/tap/tap_bpf.h I
suggest adding it, for example

# elif defined(__arm__)
#  define __NR_bpf 386

By looking at Linux source code

https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fel

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ixi
r.free-

electrons.com%2Flinux%2Fv4.15%2Fsource%2Ftools%2Fbuild%2Ffeature%2

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Ftest-

bpf.c%23L6&data=02%7C01%7Cophirmu%40mellanox.com%7C19f50ad7f27

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34d00173808d56894c997%7Ca652971c7d2e4d9ba6a4d149256f461b%7C0%

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7C0%7C636529910613736017&sdata=ynsxHG9fvao4LyfWLo4GVJjlKNmcF0q

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0BkFocJyarAE%3D&reserved=0
I am not sure, Is eBPF support available for arm32 support?

TAP eBPF has a graceful approach: it must successfully compile on all
Linux distributions. If a specific kernel cannot support eBPF it will
gracefully refuse the eBPF netlink message sent to it.
Thus, there is no harm even if there is no eBPF support available for arm32.

OK. But, To enable grace full refuse, we should not any random system call
number like #define __NR_bpf 386.
It should at least unused for arm32.

For arm - system call 386 seems to be used only for eBPF
http://elixir.free-electrons.com/linux/v4.15/source/arch/arm64/include/asm/unistd32.h#L796

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You should enable TAP compilation for cases where you only need TAP

without eBPF.

Yes. It would have been better if new eBPF depended features would have
under conditional compilation flag so it it can be turned off selectively.

I am in favor of keeping configuration as simple as possible if possible.
I will issue a PR which includes arm BPF definition

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It should work for you. Can you please try it?

I don't have access to an arm32 board. I was facing cross
compilation build issue with arm32.

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If it doesn't work for you, please have a look in this link:

https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fs

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ou

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rceforge.net%2Fp%2Fpredef%2Fwiki%2FArchitectures%2F&data=02%7C01%

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7Coph

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irmu%40mellanox.com%7C19f50ad7f2734d00173808d56894c997%7Ca6529

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71c7d2e4

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d9ba6a4d149256f461b%7C0%7C0%7C636529910613736017&sdata=g5fEkG

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Gwm%2BJgR

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KyDrxJgbFII0%2B1%2BxtbT%2FE4Qy1HACEg%3D&reserved=0
where you can see more arm architecture definitions.
You should find the one suitable for you.

I guess, it is not just matter of enabling the build for arm32. It
should work at runtime too, If some can confirm following addition
in the drivers/net/tap/tap_bpf.h works then we can add it.

As mentioned above it must not work at runtime too.

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# elif defined(__arm__)
#  define __NR_bpf 386

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/tmp/dpdk/drivers/net/tap/tap_bpf_api.c: In function ‘sys_bpf’:
/tmp/dpdk/drivers/net/tap/tap_bpf_api.c:92:17: error: ‘__NR_bpf’
undeclared (first use in this function)
  return syscall(__NR_bpf, cmd, attr, size);
                 ^
/tmp/dpdk/drivers/net/tap/tap_bpf_api.c:92:17: note: each
undeclared identifier is reported only once for each function it
appears in
/tmp/dpdk/drivers/net/tap/tap_bpf_api.c:93:1: error: control
reaches end of non-void function [-Werror=return-type]  }  ^
cc1: all warnings being treated as errors

Fixes: b02d85e1 ("net/tap: add eBPF API")

Cc: Pascal Mazon <redacted>
Cc: Jan Viktorin <redacted>
Cc: Jianbo Liu <redacted>

Signed-off-by: Jerin Jacob <redacted>
---
 config/defconfig_arm-armv7a-linuxapp-gcc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/config/defconfig_arm-armv7a-linuxapp-gcc

b/config/defconfig_arm-armv7a-linuxapp-gcc
index a20b7a85f..4a55bb397 100644

--- a/config/defconfig_arm-armv7a-linuxapp-gcc
+++ b/config/defconfig_arm-armv7a-linuxapp-gcc

@@ -80,3 +80,4 @@ CONFIG_RTE_LIBRTE_BNX2X_PMD=n

CONFIG_RTE_LIBRTE_QEDE_PMD=n

CONFIG_RTE_LIBRTE_SFC_EFX_PMD=n

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CONFIG_RTE_LIBRTE_AVP_PMD=n
+CONFIG_RTE_LIBRTE_PMD_TAP=n
--

I suggest fixing the compilation issue by adding the missing
architecture system call number (as suggested above) instead of
disabling TAP compilation by default

quoted

2.16.1