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The 'PacketSize' attribute of the qSupported packet was documented to be the maximum size of the packet including the frame and checksum bytes, however this is not how it was treated in the code. In reality, PacketSize is the maximum size of the data in the RSP packets, not including the framing or checksum bytes. For instance, GDB's remote.c treats it as the maximum number of data bytes. See remote_read_bytes_1, where the size of the request is capped at PacketSize/2 (for hex-encoding). Also see gdbserver's server.cc, where the internal buffer is sized as PBUFSIZ and PBUFSIZ-1 is used as PacketSize. In gdbserver's case, the buffer is not used for any of the framing or checksum characters. (I am not certain where the -1 comes from. I think it comes from back when there were no binary packets, so packets were treated as strings with null terminators). It also seems like gdbservers in the wild treat it in this way: Embocosm doc: https://www.embecosm.com/appnotes/ean4/embecosm-howto-rsp-server-ean4-issue-2.html#id3078000 A quick glance over openocd's gdb_server.c gdb_put_packet_inner() function shows that the internal buffer also excludes the framing and checksum. Likewise, qEmu's gdbstub.c allocates PacketSize bytes for the internal packet contents, and PacketSize+4 for the full frame. Reviewed-By: Eli Zaretskii <eliz@gnu.org> Approved-By: Pedro Alves <pedro@palves.net> |
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| ChangeLog-1991-2021 | ||
| doxy-index.in | ||
| Doxyfile-base.in | ||
| Doxyfile-gdb-api.in | ||
| Doxyfile-gdb-xref.in | ||
| Doxyfile-gdbserver.in | ||
| fdl.texi | ||
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| filter-params.pl | ||
| gdb.texinfo | ||
| gpl.texi | ||
| guile.texi | ||
| lpsrc.sed | ||
| Makefile.in | ||
| psrc.sed | ||
| python.texi | ||
| refcard.tex | ||
| stabs.texinfo | ||
| stack_frame.eps | ||
| stack_frame.pdf | ||
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| stack_frame.txt | ||
