Re: [dpdk-dev] [PATCH v2] net/ixgbe: clean up rte_eth_dev_info_get

[Tiwei Bie <tiwei.bie@intel.com>]

On Mon, Feb 06, 2017 at 01:17:30PM +0800, Lu, Wenzhuo wrote:
> > -----Original Message-----
> > From: Bie, Tiwei
> > Sent: Monday, February 6, 2017 12:57 PM
> > To: Lu, Wenzhuo
> > Cc: dev@dpdk.org
> > Subject: Re: [dpdk-dev] [PATCH v2] net/ixgbe: clean up rte_eth_dev_info_get
> > 
> > On Mon, Feb 06, 2017 at 11:45:41AM +0800, Lu, Wenzhuo wrote:
> > > Hi Tiwei,
> > >
> > > > -----Original Message-----
> > > > From: Bie, Tiwei
> > > > Sent: Monday, February 6, 2017 11:08 AM
> > > > To: Lu, Wenzhuo
> > > > Cc: dev@dpdk.org
> > > > Subject: Re: [dpdk-dev] [PATCH v2] net/ixgbe: clean up
> > > > rte_eth_dev_info_get
> > > >
> > > > On Mon, Feb 06, 2017 at 10:59:42AM +0800, Lu, Wenzhuo wrote:
> > > > > Hi Tiwei,
> > > > >
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: Bie, Tiwei
> > > > > > Sent: Monday, February 6, 2017 10:51 AM
> > > > > > To: Lu, Wenzhuo
> > > > > > Cc: dev@dpdk.org
> > > > > > Subject: Re: [dpdk-dev] [PATCH v2] net/ixgbe: clean up
> > > > > > rte_eth_dev_info_get
> > > > > >
> > > > > > On Mon, Feb 06, 2017 at 10:41:28AM +0800, Lu, Wenzhuo wrote:
> > > > > > > Hi Tiwei,
> > > > > > >
> > > > > > > > -----Original Message-----
> > > > > > > > From: Bie, Tiwei
> > > > > > > > Sent: Monday, February 6, 2017 10:31 AM
> > > > > > > > To: Lu, Wenzhuo
> > > > > > > > Cc: dev@dpdk.org
> > > > > > > > Subject: Re: [dpdk-dev] [PATCH v2] net/ixgbe: clean up
> > > > > > > > rte_eth_dev_info_get
> > > > > > > >
> > > > > > > > On Mon, Feb 06, 2017 at 10:09:32AM +0800, Wenzhuo Lu wrote:
> > > > > > > > [...]
> > > > > > > > >  static void ixgbe_dcb_init(struct ixgbe_hw *hw, struct
> > > > > > > > > ixgbe_dcb_config *dcb_config); -static int
> > > > > > > > > is_ixgbe_pmd(const char *driver_name);
> > > > > > > > > +static int is_device_supported(struct rte_eth_dev *dev,
> > > > > > > > > +struct eth_driver *drv);
> > > > > > > > >
> > > > > > > >
> > > > > > > > Should be:
> > > > > > > > static bool is_device_supported(struct rte_eth_dev *dev,
> > > > > > > > struct eth_driver *drv);
> > > > > > > O, forget to change it. Thanks.
> > > > > > >
> > > > > > > >
> > > > > > > > >  /* For Virtual Function support */  static int
> > > > > > > > > eth_ixgbevf_dev_init(struct rte_eth_dev *eth_dev); @@
> > > > > > > > > -4380,16 +4380,14 @@ static int
> > > > > > > > ixgbevf_dev_xstats_get_names(__rte_unused struct rte_eth_dev
> > > > > > > > *dev,
> > > > > > > > >  	ixgbe_add_rar(dev, addr, 0, 0);  }
> > > > > > > > >
> > > > > > > > > -static int
> > > > > > > > > -is_ixgbe_pmd(const char *driver_name)
> > > > > > > > > +static bool
> > > > > > > > > +is_device_supported(struct rte_eth_dev *dev, struct
> > > > > > > > > +eth_driver
> > > > > > > > > +*drv)
> > > > > > > > >  {
> > > > > > > > > -	if (!strstr(driver_name, "ixgbe"))
> > > > > > > > > -		return -ENOTSUP;
> > > > > > > > > +	if (strcmp(dev->driver->pci_drv.driver.name,
> > > > > > > > > +		   drv->pci_drv.driver.name))
> > > > > > > > > +		return FALSE;
> > > > > > > > >
> > > > > > > >
> > > > > > > > It would be better to use `false' instead of `FALSE'.
> > > > > > > I see both 'false' and 'FALSE' are defined and used. Is there
> > > > > > > any reason that
> > > > > > 'false' is better?
> > > > > > >
> > > > > >
> > > > > > I think `true' and `false' are standard keywords defined and
> > > > > > reserved by C. So I think it would be better to use them if the
> > > > > > return type is
> > > > `bool'.
> > > > > O, there's no 'bool' in C. You have to define it. The same for 'false' and
> > 'true'.
> > > > >
> > > >
> > > > The `bool', `true' and `false' are all standard keywords defined and
> > > > reserved by C, although the stdbool.h is not used in ixgbe.
> > > >
> > > > C adds this support by introducing a new header stdbool.h:
> > > >
> > > > #ifndef __bool_true_false_are_defined
> > > > #define __bool_true_false_are_defined   1
> > > >
> > > > #ifndef __cplusplus
> > > >
> > > > #define false   0
> > > > #define true    1
> > > >
> > > > #define bool    _Bool
> > > > #if __STDC_VERSION__ < 199901L && __GNUC__ < 3 &&
> > > > !defined(__INTEL_COMPILER)
> > > > typedef int     _Bool;
> > > > #endif
> > > O, you're talking about C99. _Bool is a  keyword added by it. 'bool', 'true',
> > 'false' are  not. That's why this header file have to define them.
> > >
> > 
> > C99 added all those as keyword, although doesn't implement all of them as
> > the builtin type (e.g. int). All of them are standard keywords defined by C99.
> > The `bool', `true' and `false' are defined in section 7.16 of the C99 spec [1] and
> > implemented as macros:
> > 
> > 7.16 Boolean type and values <stdbool.h>
> > 
> > 1 The header <stdbool.h> defines four macros.
> > 
> > 2 The macro
> >           bool
> > expands to _Bool.
> > 
> > 3 The remaining three macros are suitable for use in #if preprocessing
> > directives. They are
> >           true
> > which expands to the integer constant 1,
> >           false
> > which expands to the integer constant 0, and
> >           __bool_true_false_are_defined
> > which expands to the integer constant 1.
> > 
> > 4 Notwithstanding the provisions of 7.1.3, a program may undefine and
> > perhaps then redefine the macros bool, true, and false.222)
> > 
> > Footnotes
> > 
> > 222) See ''future library directions'' (7.26.7).
> > 
> > [1] http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf
> O, I see the divergence. It's about the term 'keyword'. I only count '6.4.1 Keywords'. 
> Anyway, as both 'false'/'true' and 'FALSE'/'TRUE' are defined. I don’t know why we cannot use any of them. If 'FALSE'/'TRUE' is not preferred, better create a new patch to clean them up.
> 

I didn't say we cannot use FALSE/TRUE, I just suggested that false/true
would be better. :-)

I think the reason why introduce _Bool as builtin keyword and implement
others as macros is to provide applications the ability to redefine them
for compatibility issues. I think new code should follow the spec if
possible. :-)

Best regards,
Tiwei Bie