> From: Marc-André Lureau <marcandre.lur...@redhat.com>
>
> Since qemu 2.9, DMA write operations are allowed. However, usage of this
> interface from kernel or user-space is strongly discouraged by the
> maintainers. This patch is meant for experimentations for now.
>
Could you (or maintainers?) tell me how experimental the DMA write
operations from kernel are?
From some technical reason?
Or simply there has not been enough test yet so far?
> Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
> ---
> drivers/firmware/qemu_fw_cfg.c | 21 ++++++++++++++++++++-
> 1 file changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c
> index 54b569da3257..e2f2ad1c9c0c 100644
> --- a/drivers/firmware/qemu_fw_cfg.c
> +++ b/drivers/firmware/qemu_fw_cfg.c
> @@ -524,9 +524,28 @@ static ssize_t fw_cfg_sysfs_read_raw(struct file *filp,
> struct kobject *kobj,
> return fw_cfg_read_blob(entry->f.select, buf, pos, count, true);
> }
>
> +static ssize_t fw_cfg_sysfs_write_raw(struct file *filp, struct kobject
> *kobj,
> + struct bin_attribute *bin_attr,
> + char *buf, loff_t pos, size_t count)
> +{
> + struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
> +
> + if (!fw_cfg_dma_enabled())
> + return -ENOTSUPP;
> +
> + if (pos > entry->f.size)
> + return -EINVAL;
> +
> + if (count > entry->f.size - pos)
> + count = entry->f.size - pos;
> +
> + return fw_cfg_write_blob(entry->f.select, buf, pos, count);
> +}
> +
> static struct bin_attribute fw_cfg_sysfs_attr_raw = {
> - .attr = { .name = "raw", .mode = S_IRUSR },
> + .attr = { .name = "raw", .mode = S_IRUSR | S_IWUSR },
> .read = fw_cfg_sysfs_read_raw,
> + .write = fw_cfg_sysfs_write_raw,
> };
>
> /*
> --
> 2.14.1.146.gd35faa819
Thanks.
HATAYAMA, Daisuke
