gdb 8.0.1连接qemu时，出现“Remote 'g' packet reply is too long”

最新推荐文章于 2025-01-25 19:11:52 发布

转载最新推荐文章于 2025-01-25 19:11:52 发布 · 204 阅读

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原文链接：http://www.cnblogs.com/hustdc/p/8146117.html

本文介绍了一个关于QEMU模拟器与gdb调试器交互的问题：使用-S参数启动QEMU时，gdb会出现Remote 'g' packet reply is too long:错误。文章提供了详细的解决方案，涉及gdb源码的修改，并适用于x86_64 CPU环境。

1 原因

“Note that other tutorials also add a "-S" parameter so QEMU starts the kernel stopped, however this is ommitted deliberately. The "-S" parameter would allow gdb to set an initial breakpoint anywhere in the kernel before kernel execution begins. Unfortunately, a change made to the gdbserver in QEMU, to support debugging 32- and 16-bit guest code in an x86_64 session breaks the -S functionality. The symptoms are that gdb prints out "Remote 'g' packet reply is too long:", and fails to interact successfully with QEMU. The suggested fix is to run the QEMU until it is in 64-bit code (i.e. after the boot loader has finished and the kernel started) before connecting from gdb (omitting the -S parameter). To debug a running kernel, this is sufficient; it is the method we will take.”

2 解决办法

gdb源码根目录/gdb/remote.c里面，将

if (buf_len > 2 * rsa->sizeof_g_packet)

error (_(“Remote ‘g’ packet reply is too long: %s”), rs->buf);

修改为

if (buf_len > 2 * rsa->sizeof_g_packet) {

rsa->sizeof_g_packet = buf_len ;

for (i = 0; i < gdbarch_num_regs (gdbarch); i++) {

if (rsa->regs->pnum == -1)

continue;

if (rsa->regs->offset >= rsa->sizeof_g_packet)

rsa->regs->in_g_packet = 0;