Re: [dpdk-dev] [PATCH v3] Fix two compile issues with i686 platform

["Qiu, Michael" <michael.qiu@intel.com>]

On 12/5/2014 11:25 PM, Neil Horman wrote:
> On Fri, Dec 05, 2014 at 03:02:33PM +0000, Bruce Richardson wrote:
>> On Fri, Dec 05, 2014 at 09:22:05AM -0500, Neil Horman wrote:
>>> On Fri, Dec 05, 2014 at 04:31:47PM +0800, Chao Zhu wrote:
>>>> On 2014/12/4 17:12, Michael Qiu wrote:
>>>>> lib/librte_eal/linuxapp/eal/eal_memory.c:324:4: error: comparison
>>>>> is always false due to limited range of data type [-Werror=type-limits]
>>>>>     || (hugepage_sz == RTE_PGSIZE_16G)) {
>>>>>     ^
>>>>> cc1: all warnings being treated as errors
>>>>>
>>>>> lib/librte_eal/linuxapp/eal/eal.c(461): error #2259: non-pointer
>>>>> conversion from "long long" to "void *" may lose significant bits
>>>>>    RTE_PTR_ALIGN_CEIL((uintptr_t)addr, RTE_PGSIZE_16M);
>>>>>
>>>>> This was introuduced by commit b77b5639:
>>>>>         mem: add huge page sizes for IBM Power
>>>>>
>>>>> The root cause is that size_t and uintptr_t are 32-bit in i686
>>>>> platform, but RTE_PGSIZE_16M and RTE_PGSIZE_16G are always 64-bit.
>>>>>
>>>>> Define RTE_PGSIZE_16G only in 64 bit platform to avoid
>>>>> this issue.
>>>>>
>>>>> Signed-off-by: Michael Qiu <michael.qiu@intel.com>
>>>>> ---
>>>>>  v3 ---> v2
>>>>> 	Change RTE_PGSIZE_16G from ULL to UL
>>>>> 	to keep all entries consistent
>>>>>
>>>>>  V2 ---> v1
>>>>> 	Change two type entries to one, and
>>>>> 	leave RTE_PGSIZE_16G only valid for
>>>>> 	64-bit platform
>>>>>
>>> NACK, this is the wrong way to fix this problem.  Pagesizes are independent of
>>> architecutre.  While a system can't have a hugepage size that exceeds its
>>> virtual address limit, theres no need to do per-architecture special casing of
>>> page sizes here.  Instead of littering the code with ifdef RTE_ARCH_64
>>> everytime you want to check a page size, just convert the size_t to a uint64_t
>>> and you can allow all of the enumerated page types on all architecutres, and
>>> save yourself some ifdeffing in the process.
>>>
>>> Neil
>> While I get your point, I find it distasteful to use a uint64_t for memory sizes,
>> when there is the size_t type defined for that particular purpose.
>> However, I suppose that reducing the number of #ifdefs compared to using the
>> "correct" datatypes for objects is a more practical optino - however distastful
>> I find it.
> size_t isn't defined for memory sizes in the sense that we're using them here.
> size_t is meant to address the need for a type to describe object sizes on a
> particular system, and it itself is sized accordingly (32 bits on a 32 bit arch,
> 64 on 64), so that you can safely store a size that the system in question might
> maximally allocate/return.  In this situation we are describing memory sizes
> that might occur no a plurality of arches, and so size_t is inappropriate
> because it as a type is not sized for anything other than the arch it is being
> built for.  The pragmatic benefits of ennumerating page sizes in a single
> canonical location far outweigh the desire to use a misappropriated type to
> describe them.

Neil,

This patch fix two compile issues, and we need to do *dpdk testing
affairs*,  if it is blocked in build stage, we can do *nothing* for testing.

I've get you mind and your concern. But we should take care of changing
the type of "hugepage_sz", because lots of places using it.

Would you mind if we consider this as hot fix, and we can post a better
fix later(like in dpdk 2.0)? Otherwise all test cycle are blocked.

Thanks,
Michael
> Neil
>
>