Re: How to printk unsigned long long variable?

From: jidong xiao
Date: Fri Jun 15 2007 - 12:18:23 EST

dma_mask should be a pointer, I mean, the element in struct device, see below,

struct device {
struct list_head node; /* node in sibling list */
struct list_head bus_list; /* node in bus's list */
struct list_head driver_list;
struct list_head children;
struct device * parent;

struct kobject kobj;
char bus_id[BUS_ID_SIZE]; /* position on parent bus */

struct bus_type * bus; /* type of bus device is on */
struct device_driver *driver; /* which driver has allocated this
device */
void *driver_data; /* data private to the driver */
void *platform_data; /* Platform specific data (e.g. ACPI,
BIOS data relevant to device) */
struct dev_pm_info power;

u32 detach_state; /* State to enter when device is
detached from its driver. */

u64 *dma_mask; /* dma mask (if dma'able device) */
u64 coherent_dma_mask;/* Like dma_mask, but for
alloc_coherent mappings as
not all hardware supports
64 bit addresses for consistent
allocations such descriptors. */

struct list_head dma_pools; /* dma pools (if dma'ble) */

struct dma_coherent_mem *dma_mem; /* internal for coherent mem
override */

void (*release)(struct device * dev);

Jason Xiao

On 6/16/07, Roland Dreier <rdreier@xxxxxxxxx> wrote:
> Is this right?

> dev->dev.dma_mask = bus->controller->dma_mask;
> printk(KERN_ERR "hey,jason,see,dma_mask is
> %llu\n",*(dev->dev.dma_mask));

No, why do you have the '*' -- dma_mask isn't a pointer, is it?

You probably want:

printk(KERN_ERR "hey,jason,see,dma_mask is %llx\n",
(unsigned long long) dev->dev.dma_mask);

(I would use a "%llx" format because masks are much clearer in hex).
The cast to unsigned long long is there because u64 is just unsigned
long on some 64-bit platforms, so you get a warning about the format
not matching on some architectures without the cast.

- R.

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