linux-kernel - Re: [PATCH v3 2/3] uio_pci_generic: add MSI/MSI-X support

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Date:	Mon, 5 Oct 2015 09:41:22 +0100
From:	Stephen Hemminger <stephen@...workplumber.org>
To:	Vlad Zolotarov <vladz@...udius-systems.com>
Cc:	linux-kernel@...r.kernel.org, mst@...hat.com, hjk@...sjkoch.de,
	corbet@....net, gregkh@...uxfoundation.org,
	bruce.richardson@...el.com, avi@...udius-systems.com,
	gleb@...udius-systems.com, alexander.duyck@...il.com
Subject: Re: [PATCH v3 2/3] uio_pci_generic: add MSI/MSI-X support

On Sun,  4 Oct 2015 23:43:17 +0300
Vlad Zolotarov <vladz@...udius-systems.com> wrote:

> +static int setup_maps(struct pci_dev *pdev, struct uio_info *info)
> +{
> +	int i, m = 0, p = 0, err;
> +	static const char * const bar_names[] = {
> +		"BAR0",	"BAR1",	"BAR2",	"BAR3",	"BAR4",	"BAR5",
> +	};
> +
> +	for (i = 0; i < ARRAY_SIZE(bar_names); i++) {
> +		unsigned long start = pci_resource_start(pdev, i);
> +		unsigned long flags = pci_resource_flags(pdev, i);
> +		unsigned long len = pci_resource_len(pdev, i);
> +
> +		if (start == 0 || len == 0)
> +			continue;
> +
> +		if (flags & IORESOURCE_MEM) {
> +			void __iomem *addr;
> +
> +			if (m >= MAX_UIO_MAPS)
> +				continue;
> +
> +			addr = ioremap(start, len);
> +			if (addr == NULL) {
> +				err = -EINVAL;
> +				goto fail;
> +			}
> +
> +			info->mem[m].name = bar_names[i];
> +			info->mem[m].addr = start;
> +			info->mem[m].internal_addr = addr;
> +			info->mem[m].size = len;
> +			info->mem[m].memtype = UIO_MEM_PHYS;
> +			++m;
> +		} else if (flags & IORESOURCE_IO) {
> +			if (p >= MAX_UIO_PORT_REGIONS)
> +				continue;
> +
> +			info->port[p].name = bar_names[i];
> +			info->port[p].start = start;
> +			info->port[p].size = len;
> +			info->port[p].porttype = UIO_PORT_X86;
> +			++p;
> +		}
> +	}
> +
> +	return 0;
> +fail:
> +	for (i = 0; i < m; i++) {
> +		iounmap(info->mem[i].internal_addr);
> +		info->mem[i].internal_addr = NULL;
> +	}
> +
> +	return err;
> +

I wonder do we really have to setup all the BAR's in uio_pci_generic?
The DPDK code works with uio_pci_generic already, and it didn't setup the BAR's.
One possible issue is that without that maybe kernel would not know about the
region used for MSI-X vectors table.
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