Re: [dpdk-dev] [PATCH] fm10k: fix the compilation on big endian platforms

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2015-08-03 19:32, Chao Zhu:
> On 2015/8/3 17:06, Thomas Monjalon wrote:
> > 2015-08-03 14:31, Chao Zhu:
> >> The rte_cpu_to_le_32 function can't be used to define const variables
> >> because it has different implementation on big endian platforms. If
> >> doing so, it will cause 'initializer element is not constant' compiling
> >> error. This patch fixes this problem.
> >> --- a/drivers/net/fm10k/base/fm10k_tlv.c
> >> +++ b/drivers/net/fm10k/base/fm10k_tlv.c
> > 
> > You cannot change a base driver file except the osdep header where
> > FM10K_CPU_TO_LE32 is defined.
> >
> > I don't understand why it doesn't give you a constant, given this definition:
> >
> > #define rte_bswap32(x) ((uint32_t)(__builtin_constant_p(x) ?        \
> >                     rte_constant_bswap32(x) :        \
> >                     rte_arch_bswap32(x)))
> >
> > Have you tried CONFIG_RTE_FORCE_INTRINSICS=y ?
> > It should trigger this definition:
> >
> > #define rte_bswap32(x) __builtin_bswap32(x)
> 
> Yes.  CONFIG_RTE_FORCE_INTRINSICS=y works on Power Big endian.  But if I 
> turn off this, the error happens.  Seems rte_constant_bswap32 doesn't 
> work on Power8? I'll try to check it.

The tile arch force intrinsics:
	http://dpdk.org/browse/dpdk/tree/config/defconfig_tile-tilegx-linuxapp-gcc#n39
	http://dpdk.org/browse/dpdk/tree/lib/librte_eal/common/include/arch/tile/rte_byteorder.h#n36
I don't know wether it was for the same reason.