% PT_IMAGE_SET_CALLBACK(3)
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# NAME
pt_image_set_callback - set a traced memory image read memory callback
# SYNOPSIS
| **\#include `<intel-pt.h>`**
|
| **typedef int (read_memory_callback_t)(uint8_t \**buffer*, size_t *size*,**
| **const struct pt_asid \**asid*,**
| **uint64_t *ip*, void \**context*);**
|
| **int pt_image_set_callback(struct pt_image \**image*,**
| **read_memory_callback_t \**callback*,**
| **void \**context*);**
Link with *-lipt*.
# DESCRIPTION
**pt_image_set_callback**() sets the function pointed to by *callback* as the
read-memory callback function in the *pt_image* object pointed to by *image*.
Any previous read-memory callback function is replaced. The read-memory
callback function can be removed by passing NULL as *callback* argument.
When the Intel(R) Processor Trace (Intel PT) instruction flow decoder that is
using *image* tries to read memory from a location that is not contained in any
of the file sections in *image*, it calls the read-memory callback function with
the following arguments:
buffer
: A pre-allocated memory buffer to hold the to-be-read memory. The callback
function shall provide the read memory in that buffer.
size
: The size of the memory buffer pointed to by the *buffer* argument.
asid
: The address-space identifier specifying the process, guest, or hypervisor,
in which context the *ip* argument is to be interpreted. See
**pt_image_add_file**(3).
ip
: The virtual address from which *size* bytes of memory shall be read.
context
: The *context* argument passed to **pt_image_set_callback**().
The callback function shall return the number of bytes read on success (no more
than *size*) or a negative *pt_error_code* enumeration constant in case of an
error.
# RETURN VALUE
**pt_image_set_callback**() returns zero on success or a negative
*pt_error_code* enumeration constant in case of an error.
# ERRORS
pte_invalid
: If the *image* argument is NULL.
# SEE ALSO
**pt_image_alloc**(3), **pt_image_free**(3), **pt_image_add_file**(3),
**pt_image_add_cached**(3), pt_image_copy**(3),
**pt_image_remove_by_filename**(3), pt_image_remove_by_asid**(3),
**pt_insn_set_image**(3), pt_insn_get_image**(3)