This patch increases the value of the MAX_PACKET_LEGNTH to 131104 from 4096 to allow the GDBState.line_buf to be large enough to accommodate the full contents of the SME ZA storage when the vector length is maximal. This is in preparation for a related patch that allows SME register visibility through remote GDB debugging.
Signed-off-by: Vacha Bhavsar <vacha.bhav...@oss.qualcomm.com> --- Changes since v4: - the value for MAX_PACKET_LENGTH is changed from 131100 to 131104 to align with a similar update made to gdbserver --- gdbstub/internals.h | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) diff --git a/gdbstub/internals.h b/gdbstub/internals.h index bf5a5c6302..87f64b6318 100644 --- a/gdbstub/internals.h +++ b/gdbstub/internals.h @@ -11,7 +11,27 @@ #include "exec/cpu-common.h" -#define MAX_PACKET_LENGTH 4096 +/* +* Most "large" transfers (e.g. memory reads, feature XML +* transfer) have mechanisms in the gdb protocol for splitting +* them. However, register values in particular cannot currently +* be split. This packet size must therefore be at least big enough +* for the worst-case register size. Currently that is Arm SME +* ZA storage with a 256x256 byte value. We also must account +* for the conversion from raw data to hex in gdb_memtohex(), +* which writes 2 * size bytes, and for other protocol overhead +* including command, register number and checksum which add +* another 4 bytes of overhead. However, to be consistent with +* the changes made in gdbserver to address this same requirement, +* we add a total of 32 bytes to account for protocol overhead +* (unclear why specifically 32 bytes), bringing the value of +* MAX_PACKET_LENGTH to 2 * 256 * 256 + 32 = 131104. +* +* The commit making this change for gdbserver can be found here: +* https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h= +* b816042e88583f280ad186ff124ab84d31fb592b +*/ +#define MAX_PACKET_LENGTH 131104 /* * Shared structures and definitions -- 2.34.1
