T-Kernel Specification (1.B0.02)

224 CHAPTER 5. T-KERNEL/SM
5.2.4 Get Physical Address
• INT CnvPhysicalAddr( VP vaddr, INT len, VP *paddr )
vaddr
len
paddr
return code
Local address
Memory space size (in bytes)
Returns physical address
Returns size (in bytes) of physical address contiguous space, or error
Gets the physical address corresponding to logical address vaddr, returning the result in paddr.
This function also passes in the return code the size of contiguous space included in len bytes
from vaddr. Accordingly, only the space of the size passed in the return code starting from paddr
is valid.
The space for which the physical address is obtained must be locked (made resident).
On the assumption of DMA transfer, memory caching is turned off for the space whose physical
address is obtained (the memory space starting from paddr of the size passed in the return code).
When the space is made nonresident (unlocked), caching goes back on.
Note that if a hardware limitation makes it disable to make memory cached off partly, the system
call flush the cache memory (that is, write back it and make it disable).
E MACV
5.2.5 Map Memory
The memory does not exist
• ER MapMemory( VP paddr, INT len, UINT attr, VP *laddr )
Maps len bytes area which starts from paddr in the physical address to logical area returning the
logical address in *laddr.
The logical address is not to be specified, automatically allocated.
If paddr = NULL is specified, some continuous memory in physical memory is automatically
allocated and mapped to logical area.
The mapped logical area has attributes specified with attr
attr := (MM_USER || MM_SYTEM ) | [MM_READ] | [MM_WRITE] | [MM_EXECUTE] | [MM_CDIS]
MM USER
MM SYSTEM
MM READ
MM WRITE
MM EXECUTE
MM CDIS
User level access
System level access
Read access
Write access
Execution
Disable cache
These symbols differ from every machines. It requires these symbols to use. Some machines need
other attributes except for these show above.
E LIMIT
E NOMEM
Insufficient logical area for mapping
Insufficient memory
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T-Kernel 1.B0.02