Re: [PATCH v3 2/3] dma/ae4dma: add control path operations

[Stephen Hemminger <stephen@networkplumber.org>]

On Sat, 27 Jun 2026 08:09:09 +0800
fengchengwen <fengchengwen@huawei.com> wrote:

> >  
> > +static int
> > +ae4dma_dev_configure(struct rte_dma_dev *dev __rte_unused,
> > +		const struct rte_dma_conf *dev_conf,
> > +		uint32_t conf_sz)
> > +{
> > +	if (sizeof(struct rte_dma_conf) != conf_sz)
> > +		return -EINVAL;  
> 
> This may break ABI compatible

Ignore that suggestion. This is a reasonable way to handle new configuration
functions. You need/want a minimal set of values. If rte_dma_conf grows in size
then the code can add compatability; by requiring a minimum set of values
and then setting the rest to zero.

Something like

static int
ae4dma_dev_configure(struct rte_dma_dev *dev __rte_unused,
		const struct rte_dma_conf *dev_conf,
		size_t conf_sz)
{
	if (conf_sz < sizeof(struct orig_rte_dma_conf))
		return -EINVAL;

	struct rte_dma_conf conf;
	memcpy(&conf, dev_conf, RTE_MIN(conf_sz, sizeof(conf)));
        dev_conf = &conf;

Looking at rte_dma_conf the structure has holes and dmadev lib
doesn't validate undefined flags, so it already has future ABI problems.