From: Simon Marchi <simark@simark.ca>
To: joel@rtems.org
Cc: gdb@sourceware.org, Nick Clifton <nickc@redhat.com>
Subject: Re: Running programs on aarch64 simulator
Date: Fri, 8 May 2020 13:17:16 -0400 [thread overview]
Message-ID: <802bfcc2-2a74-ef30-eca0-b247a6d5b8f1@simark.ca> (raw)
In-Reply-To: <CAF9ehCUyGMc2mQW_n65saKx7jNd4R_-DGtcews-yDEbdf88NLg@mail.gmail.com>
On 2020-05-08 12:57 p.m., Joel Sherrill wrote:
> On all the elf/eabi targets I have tried over the years, CPU-elf-gcc produced an a.out that was linked with the installed libgloss. I randomly had an sh-elf toolchain laying around and it worked like "sh-elf-gcc m.c" and then both sh-elf-gdb and sh-elf-run could run it on the gdb simulator.
>
> The aarch64-elf toolchain installs 4 .specs files from libgloss but adding -specs XXX and trying each with the gdb simulator (via aarch64-elf-run) all fail.
>
> home/joel/test-gcc/install-master/aarch64-elf/lib/aem-validation.specs
> /home/joel/test-gcc/install-master/aarch64-elf/lib/aem-ve.specs
> /home/joel/test-gcc/install-master/aarch64-elf/lib/nosys.specs
> /home/joel/test-gcc/install-master/aarch64-elf/lib/rdimon.specs
Ok, I am not familiar with that.
Well, it did work for me to build with:
$ aarch64-none-elf-gcc test.c -g3 -O0 -o test -specs=nosys.specs
I didn't have to provide my own _exit. According to the DWARF info, the _exit now
included in my program comes from:
/tmp/dgboter/bbs/rhev-vm1--rhe6x86_64/buildbot/rhe6x86_64--aarch64-none-elf/build/src/newlib-cygwin/libgloss/libnosys/_exit.c
>
> This seems to be an odd case where there is a simulator in the source tree and there is no clear way to use it. Assuming it works.
It's also possible to run it directly like this:
$ ./sim/aarch64/run gdb/test
core: 8 byte write to unmapped address 0xfffffff0 at 0x0
program stopped with signal 11 (Segmentation fault).
The result is the same as when I ran it through GDB. I have no idea if it's the sim that
is faulty, or the binary needs to be compiled differently.
>
> Program received signal SIGSEGV, Segmentation fault.
> 0x0000000000000000 in ?? ()
>
>
> That matches what luck I had on master. I suspect that is a mismatch between
> the address map of the simulator and whatever the default linker script does.
Perhaps. With the ARM simulator, when I do "starti" in GDB, I see that it starts
executing at the ELF file's entry point. With the AArch64 simulator, it starts
at 0 (the entry point of the ELF is not 0). So I also suspect that the initial
PC is not right.
>
> I did not push the investigation further.
>
>
> I think Nick may be the key to getting an answer here.
Added him in CC, we'll see :).
Simon
next prev parent reply other threads:[~2020-05-08 17:17 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-08 13:44 Joel Sherrill
2020-05-08 16:09 ` Simon Marchi
2020-05-08 16:57 ` Joel Sherrill
2020-05-08 17:17 ` Simon Marchi [this message]
2020-05-11 2:35 ` Simon Marchi
2020-05-11 14:26 ` Nick Clifton
2020-05-11 14:40 ` Joel Sherrill
2020-05-11 17:58 ` Jim Wilson
2020-05-11 18:30 ` Joel Sherrill
2020-05-11 22:13 ` Jim Wilson
2020-05-08 16:16 ` Luis Machado
2020-05-08 16:44 ` Joel Sherrill
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