ethdev: reserve space in main structs for extension
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Commit Message
The struct rte_eth_dev and rte_eth_dev_data are supposed
to be used internally only, but there is a chance that
increasing their size would break ABI for some applications.
In order to allow smooth addition of features without breaking
ABI compatibility, some space is reserved.
Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
---
lib/librte_ethdev/rte_ethdev_core.h | 6 ++++++
1 file changed, 6 insertions(+)
Comments
On Thu, 7 Nov 2019 23:15:24 +0100
Thomas Monjalon <thomas@monjalon.net> wrote:
> The struct rte_eth_dev and rte_eth_dev_data are supposed
> to be used internally only, but there is a chance that
> increasing their size would break ABI for some applications.
> In order to allow smooth addition of features without breaking
> ABI compatibility, some space is reserved.
>
> Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
> ---
> lib/librte_ethdev/rte_ethdev_core.h | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/lib/librte_ethdev/rte_ethdev_core.h b/lib/librte_ethdev/rte_ethdev_core.h
> index 392aea8e6b..ea8dd1d9ba 100644
> --- a/lib/librte_ethdev/rte_ethdev_core.h
> +++ b/lib/librte_ethdev/rte_ethdev_core.h
> @@ -698,6 +698,9 @@ struct rte_eth_dev {
> struct rte_eth_rxtx_callback *pre_tx_burst_cbs[RTE_MAX_QUEUES_PER_PORT];
> enum rte_eth_dev_state state; /**< Flag indicating the port state */
> void *security_ctx; /**< Context for security ops */
> +
> + uint64_t reserved_64s[4]; /**< Reserved for future fields */
> + void *reserved_ptrs[4]; /**< Reserved for future fields */
> } __rte_cache_aligned;
>
> struct rte_eth_dev_sriov;
> @@ -764,6 +767,9 @@ struct rte_eth_dev_data {
> /**< Switch-specific identifier.
> * Valid if RTE_ETH_DEV_REPRESENTOR in dev_flags.
> */
> +
> + uint64_t reserved_64s[4]; /**< Reserved for future fields */
> + void *reserved_ptrs[4]; /**< Reserved for future fields */
> } __rte_cache_aligned;
>
> /**
Void * is 32 bits on 32 bit architectures is that helpful or not?
08/11/2019 04:41, Stephen Hemminger:
> On Thu, 7 Nov 2019 23:15:24 +0100
> Thomas Monjalon <thomas@monjalon.net> wrote:
>
> > The struct rte_eth_dev and rte_eth_dev_data are supposed
> > to be used internally only, but there is a chance that
> > increasing their size would break ABI for some applications.
> > In order to allow smooth addition of features without breaking
> > ABI compatibility, some space is reserved.
> >
> > Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
> > ---
> > @@ -764,6 +767,9 @@ struct rte_eth_dev_data {
> > +
> > + uint64_t reserved_64s[4]; /**< Reserved for future fields */
> > + void *reserved_ptrs[4]; /**< Reserved for future fields */
> > } __rte_cache_aligned;
>
> Void * is 32 bits on 32 bit architectures is that helpful or not?
That's why I reserved separately uint and pointers.
If we need to add a pointer, we decrease the size of the pointer array
to keep the same struct size on all archs.
On 11/7/2019 10:15 PM, Thomas Monjalon wrote:
> The struct rte_eth_dev and rte_eth_dev_data are supposed
> to be used internally only, but there is a chance that
> increasing their size would break ABI for some applications.
> In order to allow smooth addition of features without breaking
> ABI compatibility, some space is reserved.
>
> Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Acked-by: Ferruh Yigit <ferruh.yigit@intel.com>
On 11/8/19 12:57 PM, Ferruh Yigit wrote:
> On 11/7/2019 10:15 PM, Thomas Monjalon wrote:
>> The struct rte_eth_dev and rte_eth_dev_data are supposed
>> to be used internally only, but there is a chance that
>> increasing their size would break ABI for some applications.
>> In order to allow smooth addition of features without breaking
>> ABI compatibility, some space is reserved.
>>
>> Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
> Acked-by: Ferruh Yigit <ferruh.yigit@intel.com>
Acked-by: Andrew Rybchenko <arybchenko@solarflare.com>
@@ -698,6 +698,9 @@ struct rte_eth_dev {
struct rte_eth_rxtx_callback *pre_tx_burst_cbs[RTE_MAX_QUEUES_PER_PORT];
enum rte_eth_dev_state state; /**< Flag indicating the port state */
void *security_ctx; /**< Context for security ops */
+
+ uint64_t reserved_64s[4]; /**< Reserved for future fields */
+ void *reserved_ptrs[4]; /**< Reserved for future fields */
} __rte_cache_aligned;
struct rte_eth_dev_sriov;
@@ -764,6 +767,9 @@ struct rte_eth_dev_data {
/**< Switch-specific identifier.
* Valid if RTE_ETH_DEV_REPRESENTOR in dev_flags.
*/
+
+ uint64_t reserved_64s[4]; /**< Reserved for future fields */
+ void *reserved_ptrs[4]; /**< Reserved for future fields */
} __rte_cache_aligned;
/**