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From: "tankut.baris.aktemur at intel dot com"
 <sourceware-bugzilla@sourceware.org>
To: gdb-prs@sourceware.org
Subject: [Bug server/24751] doc: Can 'm' return partial read?
Date: Thu, 14 Mar 2024 12:32:10 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D24751

Baris Aktemur <tankut.baris.aktemur at intel dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tankut.baris.aktemur@intel.
                   |                            |com

--- Comment #1 from Baris Aktemur <tankut.baris.aktemur at intel dot com> -=
--
The `gdb_read_memory` function's comment reads

```
/* Read trace frame or inferior memory.  Returns the number of bytes
   actually read, zero when no further transfer is possible, and -1 on
   error.  Return of a positive value smaller than LEN does not
   indicate there's no more to be read, only the end of the transfer.
   E.g., when GDB reads memory from a traceframe, a first request may
   be served from a memory block that does not cover the whole request
   length.  A following request gets the rest served from either
   another block (of the same traceframe) or from the read-only
   regions.  */
```

The code that's about the traceframe is

```
      if (traceframe_read_mem (cs.current_traceframe,
                               memaddr, myaddr, len, &nbytes))
        return -1;
      /* Data read from trace buffer, we're done.  */
      if (nbytes > 0)
        return nbytes;
```

I checked the code of `traceframe_read_mem`.  It may indeed return a partial
result, indicated in `nbytes` above.

Based on these, the function comment and the documentation seem mostly accu=
rate
to me.  If the documentation is updated as follows, would it be better?

"The reply may contain fewer addressable memory units than requested if the
server read from a traceframe and was able to read only part of the region =
of
memory."

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