[PATCH libpciaccess 2/2] linux: Implement map_legacy

[Jeremy Huddleston]

I don't like that this has a side effect of changing errno since it returns errno, but I'm not sure if that promise is made by libpciaccess.  My guess is that libpciaccess clients don't care about the errno side effect.

Why is the sys-fs based fd opened with O_RDWR rather than flags?

On May 10, 2011, at 14:56, Adam Jackson wrote:

> Signed-off-by: Adam Jackson <ajax at redhat.com>
> ---
> src/linux_sysfs.c |   46 ++++++++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 46 insertions(+), 0 deletions(-)
> 
> diff --git a/src/linux_sysfs.c b/src/linux_sysfs.c
> index 1832ee7..850f92f 100644
> --- a/src/linux_sysfs.c
> +++ b/src/linux_sysfs.c
> @@ -836,6 +836,50 @@ pci_device_linux_sysfs_write8(struct pci_io_handle *handle, uint32_t port,
>     pwrite(handle->fd, &data, 1, port + handle->base);
> }
> 
> +static int
> +pci_device_linux_sysfs_map_legacy(struct pci_device *dev, pciaddr_t base,
> +				  pciaddr_t size, int write_enable, void **addr)
> +{
> +    char name[PATH_MAX];
> +    int flags = O_RDONLY;
> +    int prot = PROT_READ;
> +    int fd;
> +
> +    if (write_enable) {
> +	flags |= O_WRONLY;
> +	prot |= PROT_WRITE;
> +    }
> +
> +    /* First check if there's a legacy memory method for the device */
> +    while (dev) {
> +	snprintf(name, PATH_MAX, "/sys/class/pci_bus/%04x:%02x/legacy_mem",
> +		 dev->domain, dev->bus);
> +
> +	fd = open(name, O_RDWR);
> +	if (fd >= 0)
> +	    break;
> +
> +	dev = pci_device_get_parent_bridge(dev);
> +    }
> +
> +    /* If not, /dev/mem is the best we can do */
> +    if (!dev)
> +	fd = open("/dev/mem", flags);
> +
> +    if (fd < 0)
> +	return errno;
> +
> +    *addr = mmap(NULL, size, prot, MAP_SHARED, fd, base);
> +    if (*addr == MAP_FAILED) {
> +	int ret = errno;
> +	close(fd);
> +	return ret;
> +    }
> +
> +    close(fd);
> +    return 0;
> +}
> +
> static const struct pci_system_methods linux_sysfs_methods = {
>     .destroy = NULL,
>     .destroy_device = NULL,
> @@ -861,4 +905,6 @@ static const struct pci_system_methods linux_sysfs_methods = {
>     .write32 = pci_device_linux_sysfs_write32,
>     .write16 = pci_device_linux_sysfs_write16,
>     .write8 = pci_device_linux_sysfs_write8,
> +
> +    .map_legacy = pci_device_linux_sysfs_map_legacy,
> };
> -- 
> 1.7.5
> 
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