Re: [dpdk-dev] [PATCH] librte_lpm: define tbl entry reversely for big endian

[Bruce Richardson <bruce.richardson@intel.com>]

On Thu, Mar 05, 2015 at 02:12:12AM +0000, Xuelin Shi wrote:
> Hi Bruce,
> 
> Yes, it needs to swap the fields. The bit field is first identified as the uint8_t and then packed.
> 
> Thanks,
> Shi xuelin
> 
Am I right in thinking that this patch set supercedes that for
"lpm: use field access instead of type conversion" http://dpdk.org/dev/patchwork/patch/3132/ ?

> > -----Original Message-----
> > From: Bruce Richardson [mailto:bruce.richardson@intel.com]
> > Sent: Wednesday, March 04, 2015 18:48
> > To: Shi Xuelin-B29237
> > Cc: thomas.monjalon@6wind.com; dev@dpdk.org
> > Subject: Re: [PATCH] librte_lpm: define tbl entry reversely for big
> > endian
> > 
> > On Wed, Mar 04, 2015 at 02:34:12PM +0800, xuelin.shi@freescale.com wrote:
> > > From: Xuelin Shi <xuelin.shi@freescale.com>
> > >
> > > This module uses type conversion between struct and int.
> > > Also truncation and comparison is used with this int.
> > > It is not safe for different endian arch.
> > >
> > > Add ifdef for big endian struct to fix this issue.
> > >
> > > Signed-off-by: Xuelin Shi <xuelin.shi@freescale.com>
> > > ---
> > >  lib/librte_lpm/rte_lpm.h | 19 +++++++++++++++++++
> > >  1 file changed, 19 insertions(+)
> > >
> > > diff --git a/lib/librte_lpm/rte_lpm.h b/lib/librte_lpm/rte_lpm.h index
> > > 1af150c..08a2859 100644
> > > --- a/lib/librte_lpm/rte_lpm.h
> > > +++ b/lib/librte_lpm/rte_lpm.h
> > > @@ -96,6 +96,7 @@ extern "C" {
> > >  /** Bitmask used to indicate successful lookup */
> > >  #define RTE_LPM_LOOKUP_SUCCESS          0x0100
> > >
> > > +#if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN
> > >  /** @internal Tbl24 entry structure. */  struct rte_lpm_tbl24_entry {
> > >  	/* Stores Next hop or group index (i.e. gindex)into tbl8. */ @@
> > > -117,6 +118,24 @@ struct rte_lpm_tbl8_entry {
> > >  	uint8_t valid_group :1; /**< Group validation flag. */
> > >  	uint8_t depth       :6; /**< Rule depth. */
> > >  };
> > > +#else
> > > +struct rte_lpm_tbl24_entry {
> > > +	uint8_t depth 	    :6;
> > > +	uint8_t ext_entry   :1;
> > > +	uint8_t valid	    :1;
> > 
> > Since endianness only refers to the order of bytes within a word, do the
> > bitfields within the uint8_t really need to be swapped around too?
> > 
> > /Bruce
> 
> > 
> > > +	union {
> > > +		uint8_t tbl8_gindex;
> > > +		uint8_t next_hop;
> > > +	};
> > > +};
> > > +
> > > +struct rte_lpm_tbl8_entry {
> > > +	uint8_t depth 	    :6;
> > > +	uint8_t valid_group :1;
> > > +	uint8_t valid	    :1;
> > > +	uint8_t next_hop;
> > > +};
> > > +#endif
> > >
> > >  /** @internal Rule structure. */
> > >  struct rte_lpm_rule {
> > > --
> > > 1.9.1
> > >