KnIoMapMem()

This function is declared in the coresrv/io/mmio.h file.

Retcode KnIoMapMem(Handle rid, rtl_uint32_t prot, rtl_uint32_t attr,

void **addr, Handle *handle);

This function maps the registered memory area that was assigned the handle rid to the address space of the process.

You can use the prot and attr input parameters to change the memory area protection attributes, or to disable caching.

Output parameters:

• addr is the pointer to the starting address of the virtual memory area.
• handle refers to the handle of the virtual memory area.

Returns rcOk if successful.

prot refers to the attributes of memory area protection via MMU, with the following possible values:

• VMM_FLAG_READ – allow read.
• VMM_FLAG_WRITE – allow write.
• VMM_FLAG_READ | VMM_FLAG_WRITE – allow read and write.
• VMM_FLAG_RWX_MASK or VMM_FLAG_READ | VMM_FLAG_WRITE | VMM_FLAG_EXECUTE – full access to the memory area (these entries are equivalent).

attr – memory area attributes. Possible values:

• VMM_FLAG_CACHE_DISABLE – disable caching.
• VMM_FLAG_LOW_GUARD and VMM_FLAG_HIGH_GUARD add a protective page before and after the allocated memory, respectively.
• VMM_FLAG_ALIAS – flag indicates that the memory area may have multiple virtual addresses.

Example

static Retcode MemInit(IOMem *resource)

{

Retcode rc = rcFail;

rc = KnRegisterPhyMem(resource->base,

resource->size,

&resource->handle);

if (rc == rcOk)

rc = KnIoMapMem(resource->handle,

VMM_FLAG_READ | VMM_FLAG_WRITE,

VMM_FLAG_CACHE_DISABLE,

(void **) &resource->addr, &resource->permitHandle);

if (rc == rcOk)

resource->addr = ((rtl_uint8_t *) resource->addr

+ resource->offset);

return rc;

}

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