Re: [dpdk-dev] [EXT] Re: [PATCH v5 1/3] net/thunderx: enable build only on 64-bit Linux

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 10/4/2021 1:54 PM, Pavan Nikhilesh Bhagavatula wrote:
>> On 10/4/2021 1:01 PM, Pavan Nikhilesh Bhagavatula wrote:
>>>> On 10/4/2021 12:34 PM, Pavan Nikhilesh Bhagavatula wrote:
>>>>>> On 10/4/2021 11:02 AM, Pavan Nikhilesh Bhagavatula wrote:
>>>>>>>> On 10/4/2021 6:56 AM, pbhagavatula@marvell.com wrote:
>>>>>>>>> From: Pavan Nikhilesh <pbhagavatula@marvell.com>
>>>>>>>>>
>>>>>>>>> Due to Linux kernel AF(Admin function) driver dependency,
>> only
>>>>>>>> enable
>>>>>>>>> build for 64-bit Linux.
>>>>>>>>>
>>>>>>>>
>>>>>>>> Hi Pavan,
>>>>>>>>
>>>>>>>> Isn't it possible to provide a commit log in the kernel side etc,
>> that
>>>> let
>>>>>>>> others to verify why only 64 bit is required, or if someone want
>> to
>>>>>>>> support
>>>>>>>> 32bit that may help them to investigate the source of the
>>>> restriction.
>>>>>>>
>>>>>>> Arch 32 support is not implemented on ThunderX, so 32bit will
>> not
>>>>>> run.
>>>>>>>
>>>>>>
>>>>>> I see, is following correct:
>>>>>> All thunderx, octeonx & octeontx2 only supports VF in the DPDK,
>>>> and PF
>>>>>> is
>>>>>> supported by Linux kernel driver. And Linux kernel driver doesn't
>>>>>> support arch32.
>>>>>
>>>>> AF != PF, AF is something that manages all the shared resources
>>>> between PF/VF.
>>>>>
>>>>
>>>> I see, I though AF is part of PF functionality. Are there two different
>>>> kernel
>>>> modules for PF and AF?
>>>>
>>>> So can DPDK driver drive PF? In a way, PF by DPDK, VF by DPDK, AF
>> by
>>>> Linux
>>>> kernel driver.
>>>
>>> Yup that’s correct.
>>>
>>>>
>>>>>>
>>>>>> Is something changed in kernel driver side to drop the 32bit
>> support?
>>>>>> If it was not supported at all, what is the motivation to disable the
>>>> DPDK
>>>>>> drivers now?
>>>>>>
>>>>>
>>>>> It was never supported to begin with, motivation is that build will
>> fail if
>>>> we try to
>>>>> compile with 32b.
>>>>>
>>>>
>>>> If there is no plan to support 32bit in the kernel side, that is
>> reasonable
>>>> to
>>>> disable 32bit build, please provide above details in the commit log.
>>>>
>>>> And after above said, how much maintenance cost to support 32bit,
>> if
>>>> the build
>>>> error is on the logging format "%lx" etc .. (as we mostly have 32bit
>> build
>>>> errors), it is better to fix them using 'PRIx64' which is more proper
>> way
>>>> anyway. If there is more logical issue with 32bit pointers, I agree with
>>>> you to
>>>> disable it.
>>>> Can you please provided the build error in the commit log as record?
>>>>
>>>
>>> Apologies, I meant that all the functions that don’t fall under 64b are
>> stubbed out
>>> so the driver wouldn’t work.
>>>
>>
>> so is there build error or not?
>>
> 
> No build error.
> 

Just trying to clarify,

Linux kernel AF kernel driver only build for 64-bit Linux.
And mentioned DPDK drivers have a dependency to this kernel module.

But DPDK drivers are userspace application, can't 32-bit application
run on 64-bit Linux?

Can you please clarify what exactly is not supported?


>>>>>>>>
>>>>>>>>> Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>
>>>>>>>>> Acked-by: Jerin Jacob <jerinj@marvell.com>
>>>>>>>>> ---
>>>>>>>>>   v5 Changes
>>>>>>>>>   - s/fuction/function.
>>>>>>>>>
>>>>>>>>>   v4 Changes:
>>>>>>>>>   - Update commit message regarding dependency on AF
>> driver.
>>>>>>>>>
>>>>>>>>>   drivers/net/thunderx/meson.build | 4 ++--
>>>>>>>>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>>>>>>>>
>>>>>>>>> diff --git a/drivers/net/thunderx/meson.build
>>>>>>>> b/drivers/net/thunderx/meson.build
>>>>>>>>> index 4bbcea7f93..da665bd76f 100644
>>>>>>>>> --- a/drivers/net/thunderx/meson.build
>>>>>>>>> +++ b/drivers/net/thunderx/meson.build
>>>>>>>>> @@ -1,9 +1,9 @@
>>>>>>>>>   # SPDX-License-Identifier: BSD-3-Clause
>>>>>>>>>   # Copyright(c) 2017 Cavium, Inc
>>>>>>>>>
>>>>>>>>> -if is_windows
>>>>>>>>> +if not is_linux or not dpdk_conf.get('RTE_ARCH_64')
>>>>>>>>>       build = false
>>>>>>>>> -    reason = 'not supported on Windows'
>>>>>>>>> +    reason = 'only supported on 64-bit Linux'
>>>>>>>>>       subdir_done()
>>>>>>>>>   endif
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> 2.17.1
>>>>>>>>>
>>>>>>>
>>>>>
>>>
>