RE: [RFC 10/10] tools: PCI: Add MSI-X support

[Alan Douglas]

Hi Gustavo,

On 10 April 2018 18:15, Gustavo Pimentel wrote:
> Adds MSI-X support to the pcitest tool and modified the pcitest.sh script to
> accomodate this new type of interruption test.
> 
> Signed-off-by: Gustavo Pimentel <gustavo.pimentel@xxxxxxxxxxxx>
> ---
>  include/uapi/linux/pcitest.h |  1 +
>  tools/pci/pcitest.c          | 18 +++++++++++++++++-
>  tools/pci/pcitest.sh         | 25 +++++++++++++++++++++++++
>  3 files changed, 43 insertions(+), 1 deletion(-)
I found some possible problems when testing with the Cadence EP driver.  The problem
is that pcitest uses the BARs for tests, but we also use one for the MSI-X tables

In Cadence core the MSI-X table is in BAR0 by default, but this is configured to a size
of 0x80 in the test driver, since it is used as the test_reg_bar.  So, I changed the 
configuration to use BAR4 instead, which is configured to a size of 131072 
in pci-efp-test.c, and this gives me enough space.

However, if I run the BAR tests in pcitest before running the MSI-X tests, the
MSI-X tests fail, since the BAR content is overwritten.  It's not a problem with the 
scenario in pcitest.sh, but it would be if the module wasn't re-loaded.

So, wondering if we need to come up with some mechanism to specify that a specific
BAR will be used for MSI-X, and that its size and content shouldn't be modified by
pcitest?

Regards,
Alan