On 10/30/2017 4:24 AM, Thomas Monjalon wrote:
> 30/10/2017 10:27, Thomas Monjalon:
>> 30/10/2017 10:17, Gaëtan Rivet:
>>> Hi Ferruh,
>>>
>>> On Mon, Oct 30, 2017 at 02:00:43AM -0700, Ferruh Yigit wrote:
>>>> On 10/30/2017 1:06 AM, Gaëtan Rivet wrote:
>>>>> Hi Jerin,
>>>>>
>>>>> On Sat, Oct 28, 2017 at 11:50:52AM +0530, Jerin Jacob wrote:
>>>>>> The definition of VFIO_PRESENT is "eal_vfio.h", Fail to
>>>>>> include eal_vfio.h will result in disabling vfio.
>>>>>>
>>>>>> Fixes: 279b581c897d ("vfio: expose functions")
>>>>>>
>>>>>
>>>>> Thanks for the fix, sorry for VFIO.
>>>>> I tried to let go of VFIO_PRESENT in the PCI patchset, unfortunately I did
>>>>> not do a good-enough job.
>>>>>
>>>>> Instead of reinstating the dependency on the private eal_vfio.h header,
>>>>> I'd suggest replacing all VFIO_PRESENT references within the PCI bus by
>>>>> RTE_EAL_VFIO, and make the pci_vfio.c compilation depend on it within
>>>>> the linux Makefile. Something like:
>>>>>
>>>>> ---8<---
>>>>>
>>>>> grep -rl VFIO_PRESENT drivers/bus/pci/linux/ |while read -r file
>>>>> do sed -i 's;VFIO_PRESENT;RTE_EAL_VFIO;' $file
>>>>> done
>>>>
>>>> VFIO_PRESENT is the combination of the if user enabled VFIO and if Linux
>>>> kernel
>>>> supports it.
>>>>
>>>> Why not add same check and VFIO_PRESENT definition to rte_vfio.h:
>>>>
>>>> --- a/lib/librte_eal/common/include/rte_vfio.h
>>>> +++ b/lib/librte_eal/common/include/rte_vfio.h
>>>> @@ -34,7 +34,13 @@
>>>> #ifndef _RTE_VFIO_H_
>>>> #define _RTE_VFIO_H_
>>>>
>>>> +#if !defined(VFIO_PRESENT) && defined(RTE_EAL_VFIO)
>>>> +#include <linux/version.h>
>>>> +#if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 6, 0)
>>>> #include <linux/vfio.h>
>>>> +#define VFIO_PRESENT
>>>> +#endif /* >= 3.6.0 */
>>>> +#endif
>>>> +
>>>> +#ifdef VFIO_PRESENT
>>>>
>>>> ... Need to wrap here in case VFIO disabled ...
>>>>
>>>> #endif
>>>>
>>>
>>> It would work indeed.
>>>
>>> I mostly dislike having whole compilation units disabled silently on a
>>> linux version check. I think that if someone wanted to support kernels <
>>> 3.6, they ought to do the work of disabling RTE_EAL_VFIO.
>>>
>>> A build error could be thrown to help those users toward the right
>>> solution, but I think that the meaning of having this option enabled
>>> should be enforced: if it is enabled, it is compiled. If dependencies
>>> are not met, then the option should be disabled.
>>
>> +1 to avoid implicit disabling.
>
> To make it clear, we can disable VFIO automatically if not supported by
> the kernel at compilation time, but there should be a warning.
Gaetan suggest letting build error and push user to disable the feature. If we
let the build error, I think feature should be disabled by default.
And for VFIO, instead of disabling it by default I am for auto disable it if
kernel requirement not met, and +1 for adding a warning.
btw, that kernel version check is already in eal_vfio.h, we are already
disabling some vfio code based on kernel version check, weather add here or not.
Thanks,
ferruh
