diff options
Diffstat (limited to 'lldb/docs/lldb-gdb-remote.txt')
| -rw-r--r-- | lldb/docs/lldb-gdb-remote.txt | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/lldb/docs/lldb-gdb-remote.txt b/lldb/docs/lldb-gdb-remote.txt index b471b245f85..d8f22fe604a 100644 --- a/lldb/docs/lldb-gdb-remote.txt +++ b/lldb/docs/lldb-gdb-remote.txt @@ -1384,3 +1384,66 @@ for this region. // // on the wire. //---------------------------------------------------------------------- + +//---------------------------------------------------------------------- +// "QEnableCompression" +// +// BRIEF +// This packet enables compression of the packets that the debug stub sends to lldb. +// If the debug stub can support compression, it indictes this in the reply of the +// "qSupported" packet. e.g. +// LLDB SENDS: qSupported:xmlRegisters=i386,arm,mips +// STUB REPLIES: qXfer:features:read+;SupportedCompressions=lzfse,zlib-deflate,lz4,lzma;DefaultCompressionMinSize=384 +// +// If lldb knows how to use any of these compression algorithms, it can ask that this +// compression mode be enabled. It may optionally change the minimum packet size +// where compression is used. Typically small packets do not benefit from compression, +// as well as compression headers -- compression is most beneficial with larger packets. +// +// QEnableCompression:type:zlib-deflate; +// or +// QEnableCompression:type:zlib-deflate;minsize:512; +// +// The debug stub should reply with an uncompressed "OK" packet to indicate that the +// request was accepted. All further packets the stub sends will use this compression. +// +// Packets are compressed as the last step before they are sent from the stub, and +// decompressed as the first step after they are received. The packet format in compressed +// mode becomes one of two: +// +// $N<uncompressed payload>#00 +// +// $C<size of uncompressed payload in base10>:<compressed payload>#00 +// +// Where "#00" is the actual checksum value if noack mode is not enabled. The checksum +// value is for the "N<uncompressed payload>" or +// "C<size of uncompressed payload in base10>:<compressed payload>" bytes in the packet. +// +// The size of the uncompressed payload in base10 is provided because it will simplify +// decompression if the final buffer size needed is known ahead of time. +// +// Compression on low-latency connections is unlikely to be an improvement. Particularly +// when the debug stub and lldb are running on the same host. It should only be used +// for slow connections, and likely only for larger packets. +// +// Example compression algorithsm that may be used include +// +// zlib-deflate +// The raw DEFLATE format as described in IETF RFC 1951. With the ZLIB library, you +// can compress to this format with an initialization like +// deflateInit2 (&stream, 5, Z_DEFLATED, -15, 8, Z_DEFAULT_STRATEGY) +// and you can decompress with an initialization like +// inflateInit2 (&stream, -15) +// +// lz4 +// https://en.wikipedia.org/wiki/LZ4_(compression_algorithm) +// https://github.com/Cyan4973/lz4 +// The libcompression APIs on darwin systems call this COMPRESSION_LZ4_RAW. +// +// lzfse +// An Apple proprietary compression algorithm implemented in libcompression. +// +// lzma +// libcompression implements "LZMA level 6", the default compression for the +// open source LZMA implementation. +//---------------------------------------------------------------------- |
