Hi! I have been playing a little with this: I'm writing a kernel for both x86 and x86-64. While doing so, i'd like to debug the kernel using qemu (and it's gdb stub) and gdb. This worked very well until qemu-0.11.1 (gdb version does not seem to play any role...). From there on, debugging the 64 bit version no longer works. My sessions look like this with qemu-0.13.50 (and any version above 0.11.1, actually...):
md...@s01en22 /big/Privat/osdev/tachyon2 $ x86_64-pc-linux-gnu-gdb .build/x86_64/x86_64-tachyon GNU gdb (GDB) 7.2.50.20110103-cvs [snip] Reading symbols from /big/Privat/osdev/tachyon2/.build/x86_64/x86_64-tachyon...done. (gdb) target remote:1234 Remote debugging using :1234 0x0000000000000000 in ?? () (gdb) b boot Breakpoint 1 at 0xffffffff80119000: file /big/Privat/osdev/tachyon2/core/tachyon.boot/Entry.cc, line 25. (gdb) c Continuing. Remote 'g' packet reply is too long: 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 000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000801f0000 (gdb) quit actuallly, i _can_ debug the kernel, nut only until the long mode switch occurs. after this point: no luck... :[ now for the questions: 1) is this a problem with qemu or was qemu "fixed" and gdb has a problem? (that's why i CCd the gdb list ;)). 2) is there any plan to fix this issue? 3) is there some kind of workaround i can use (i'd be happy with an ugly/unsupported patch too, since i build all my stuff myself ;)). Thanks in advance! Regards, Markus
