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man pages section 9: DDI and DKI Kernel Functions

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Updated: July 2017



ptob - convert size in pages to size in bytes


#include <sys/ddi.h>

unsigned long ptob(unsigned long numpages);

Interface Level

Architecture independent level 1 (DDI/DKI).



Size in number of pages to convert to size in bytes.


This function returns the number of bytes that are contained in the specified number of pages. For example, if the page size is 2048, then ptob(2) returns 4096. ptob(0) returns 0.

Return Values

The return value is always the number of bytes in the specified number of pages. There are no invalid input values, and no checking will be performed for overflow in the case of a page count whose corresponding byte count cannot be represented by an unsigned long. Rather, the higher order bits will be ignored.


The ptob() function can be called from user, interrupt, or kernel context.

See Also

btop(9F), btopr(9F), ddi_ptob(9F)

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