From mboxrd@z Thu Jan 1 00:00:00 1970 From: To: Subject: Re: examining mmap()'d memory regions on linux Date: Mon, 05 Jun 2000 18:01:00 -0000 Message-id: <0006059602.AA960253227@mailserver.aerosimulation.com> X-SW-Source: 2000-06/msg00046.html >Kevin Hilman wrote on 17 May 2000: >> >> I have an app that reads/writes to an mmap()'d region. The data >> is being read and written fine because it's getting to it's final >> location (in this case a hardware device). >> >> However, if I try to examine (via 'x') these memory regions in gdb, I >> always get zeros. >> >> Does gdb support mmap()'d regions? > >Not a GDB problem. GDB asks the kernel ``can I have memory at address X >with process P''. If the kernel doesn't return it there is little GDB >can do :-) > >As a work around, you may want to add a small function to your program >that dumps out the relevant data. You can then call that from the gdb >command line. > > enjoy, > Andrew Can you elaborate on what/how the kernel (ptrace) returns zero for mmapped memory? I read the ptrace.c code for i386 and didn't see the relationship between the comments and mmap. I have the same problem with unable to examine a PCI reflective memory. I also tried a program which just mallocs memory and I couldn't see it's contents either.