On 9/6/18 10:00 am, Joel Sherrill wrote: > On Thu, Jun 7, 2018, 9:01 PM Chris Johns <chr...@rtems.org > <mailto:chr...@rtems.org>> wrote: > > and what > > discussions we need to have to decide between the "bundled kernel.so > approach" > > (the one implemented here) vs. the "FreeBSD loader.efi+hello.exe" > approach. Let > > me know! > > > > I do not think I can help too much here. I understand the loader.efi+exe > solution and it should work because all RTEMS applications we have are > statically linked (I am assuming it is here). I have not looked at the > details > being used with the -fPIC and .so solution so I cannot comment. I do have > some > concerns the relocatable exe might expose some dark corners and issues in > the > host tools we have, for example how does GDB find the base address of the > image > so you can debug it? and is this just working or is it really suppose to > work > this way? > > > All I can say is that with Deos/RTEMS, we use PIC on arm, PowerPC, and x86.
I would hope a solution like Deos did provide a seamless way to do this and I would also hope they support you. > We > have spent a lot of time debugging with gdb attached to qemu. How does GDB get the relocatable load address to map to the symbol table? The libdl code supports the same protocol/design as NetBSD and other systems in informing GDB about the address of loaded modules. There is a series of symbols and tables maintained that GDB knows to examine to find the load addresses of object files. > I haven't seen any tools issues yet. Yet? Once the path is settled it will be difficult to change so all I am asking is the detail be checked and understood. RTEMS does not support shared libraries the same way Linux or other Unix systems do. I do not understand enough of the low level and the standards all this is based on to help decide. An example of an issue where a relocatable kernel with an unknown load address creates a problem is libdl. The testsuite uses the 2-pass approach (rtems-syms --embed) which should be OK however the other approach where the symbol table is not embedded and built on the host would fail. It is a small issue but it shows how things can subtly break. Chris _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
