Re: [dpdk-dev] [PATCH v6 1/8] eal: pci: add api to rd/wr pci bar region

[Yuanhan Liu <yuanhan.liu@linux.intel.com>]

On Fri, Jan 29, 2016 at 11:51:50PM +0530, Santosh Shukla wrote:
> Introducing below api for pci bar region rd/wr.
> Api's are:
> - rte_eal_pci_read_bar
> - rte_eal_pci_write_bar
> 
> Signed-off-by: Santosh Shukla <sshukla@mvista.com>
> ---
> v5-->v6:
> - update api infor in rte_eal_version.map file
>   suggested by david manchand.
> 
>  lib/librte_eal/bsdapp/eal/eal_pci.c             |   19 ++++++++++++
>  lib/librte_eal/bsdapp/eal/rte_eal_version.map   |    3 ++
>  lib/librte_eal/common/include/rte_pci.h         |   38 +++++++++++++++++++++++
>  lib/librte_eal/linuxapp/eal/eal_pci.c           |   34 ++++++++++++++++++++
>  lib/librte_eal/linuxapp/eal/eal_pci_init.h      |    6 ++++
>  lib/librte_eal/linuxapp/eal/eal_pci_vfio.c      |   28 +++++++++++++++++
>  lib/librte_eal/linuxapp/eal/rte_eal_version.map |    3 ++
>  7 files changed, 131 insertions(+)
> 
> diff --git a/lib/librte_eal/bsdapp/eal/eal_pci.c b/lib/librte_eal/bsdapp/eal/eal_pci.c
> index 95c32c1..2e535ea 100644
> --- a/lib/librte_eal/bsdapp/eal/eal_pci.c
> +++ b/lib/librte_eal/bsdapp/eal/eal_pci.c
...
> +int rte_eal_pci_read_bar(const struct rte_pci_device *device,
> +			 void *buf, size_t len, off_t offset,
> +			 int bar_idx)
> +
> +{
> +	const struct rte_intr_handle *intr_handle = &device->intr_handle;

I'd suggest to reference this var inside pci_vfio_read/write_bar(), and
pass device as the parmater instead.

> +
> +	switch (device->kdrv) {
> +	case RTE_KDRV_VFIO:
> +		return pci_vfio_read_bar(intr_handle, buf, len,
> +					 offset, bar_idx);
> +	default:
> +		RTE_LOG(ERR, EAL, "write bar not supported by driver\n");
                                   ^^^^^
typo.


BTW, I have a question about this API. Obviously, reading/writing bar
space is supported with UIO (when memory resource is mmapped). And I
know why you introduced such 2 APIs, for reading IO bar.

So, here is the question: what are the 2 APIs for, for being gerneric
APIs to read/write bar spaces, or just to read IO bar spaces? If it's
former, the message is wrong; if it's later, you may better rename it
to rte_eal_pci_read/write_io_bar()?

David, what do you think of that?


> +		return -1;
> +	}
> +}
> +
...
> +int
> +pci_vfio_read_bar(const struct rte_intr_handle *intr_handle,
> +		  void *buf, size_t len, off_t offs, int bar_idx)
> +{
> +	if (bar_idx < VFIO_PCI_BAR0_REGION_INDEX
> +	   || bar_idx > VFIO_PCI_BAR5_REGION_INDEX) {

A minor nit: it's more nature to put the '||' at the end of expression,
instead of at the front:

    if (bar_idx < VFIO_PCI_BAR0_REGION_INDEX ||
        bar_idx > VFIO_PCI_BAR5_REGION_INDEX) {


	--yliu