91ffe0a570
For some communication channels, sending large packets can be very slow. In those cases, it may be faster to compress the contents of the packet on the target device and decompress it on the debug host system. For instance, communicating with a device using something like Bluetooth may be an environment where this tradeoff is a good one. This patch adds a new field to the response to the "qSupported" packet (which returns a "qXfer:features:" response) -- SupportedCompressions and DefaultCompressionMinSize. These tell you what the remote stub can support. lldb, if it wants to enable compression and can handle one of those algorithms, it can send a QEnableCompression packet specifying the algorithm and optionally the minimum packet size to use compression on. lldb may have better knowledge about the best tradeoff for a given communication channel. I added support to debugserver an lldb to use the zlib APIs (if -DHAVE_LIBZ=1 is in CFLAGS and -lz is in LDFLAGS) and the libcompression APIs on Mac OS X 10.11 and later (if -DHAVE_LIBCOMPRESSION=1). libz "zlib-deflate" compression. libcompression can support deflate, lz4, lzma, and a proprietary lzfse algorithm. libcompression has been hand-tuned for Apple hardware so it should be preferred if available. debugserver currently only adds the SupportedCompressions when it is being run on an Apple watch (TARGET_OS_WATCH). Comment that #if out from RNBRemote.cpp if you want to enable it to see how it works. I haven't tested this on a native system configuration but surely it will be slower to compress & decompress the packets in a same-system debug session. I haven't had a chance to add support for this to GDBRemoteCommunciationServer.cpp yet. <rdar://problem/21090180> llvm-svn: 240066 |
||
|---|---|---|
| .. | ||
| testsuite | ||
| CMakeLists.txt | ||
| building-with-debug-llvm.txt | ||
| code-signing.txt | ||
| doxygen.cfg.in | ||
| doxygen.footer | ||
| doxygen.header | ||
| doxygen.intro | ||
| lldb-for-gdb-users.txt | ||
| lldb-gdb-remote.txt | ||
| lldb.1 | ||