riscv: gdb cannot connect to rtems runnin in qemu

Fri Jan 29 14:47:42 UTC 2021

Unfortunately, may be time to characterize this so we can ask on gdb's list
what to do.

--joel

On Fri, Jan 29, 2021 at 8:38 AM <Jan.Sommer at dlr.de> wrote:

>
>
>
>
> *From:* Joel Sherrill <joel at rtems.org>
> *Sent:* Friday, January 29, 2021 3:33 PM
> *To:* Sommer, Jan <Jan.Sommer at dlr.de>
> *Cc:* Jiri Gaisler <jiri at gaisler.se>; rtems-users at rtems.org <
> users at rtems.org>
> *Subject:* Re: riscv: gdb cannot connect to rtems runnin in qemu
>
>
>
>
>
>
>
> On Fri, Jan 29, 2021 at 8:29 AM <Jan.Sommer at dlr.de> wrote:
>
> Just tried again with the rv32imac BSP.
> With this gdb works.
>
>
>
> I was poking at the gdb source and found the code in question in
> riscv-tdep.c:
>
>
>   /* In theory a binary compiled for RV32 could run on an RV64 target,
>      however, this has not been tested in GDB yet, so for now we require
>      that the requested xlen match the targets xlen.  */
>   if (abi_features.xlen != features.xlen)
>     error (_("bfd requires xlen %d, but target has xlen %d"),
>    abi_features.xlen, features.xlen);
>   /* We do support running binaries compiled for 32-bit float on targets
>      with 64-bit float, so we only complain if the binary requires more
>      than the target has available.  */
>   if (abi_features.flen > features.flen)
>     error (_("bfd requires flen %d, but target has flen %d"),
>    abi_features.flen, features.flen);
>
>
>
> I'm reading that as the qemu configuration doesn't support the floating
> point
>
> width required for 64-bit riscv.
>
>
>
> In one of my test directories, I had different qemu's for 32-bit and
> 64-bit
>
> riscv. Do you? Maybe that makes a difference.
>
>
>
> Yes, I used the 32 bit version for riscv. I used the following qemu line:
>
> qemu-system-riscv32 -nographic -machine virt -m 2G -nographic -net none
> -serial mon:stdio -bios /tmp/riscv/ticker.exe -s -S
>
>
>
> I also have a
>
> qemu-system-riscv64, but with this I have failed to get an RTEMS
> application running (neither the rv32* nor the rv64* based ones) so far.
>
>
>
> Best regards,
>
>
>
>     Jan
>
>
>
>
>
> --joel
>
>
> Best regards,
>
>     Jan
>
> > -----Original Message-----
> > From: users <users-bounces at rtems.org> On Behalf Of Jan.Sommer at dlr.de
> > Sent: Friday, January 29, 2021 3:10 PM
> > To: joel at rtems.org; jiri at gaisler.se
> > Cc: users at rtems.org
> > Subject: RE: riscv: gdb cannot connect to rtems runnin in qemu
> >
> >
> >
> > > From: Joel Sherrill <joel at rtems.org>
> > >
> > >On Fri, Jan 29, 2021 at 7:20 AM <Jan.Sommer at dlr.de> wrote:
> > >> Hello
> > >>
> > >> I just tried to debug a riscv test program running in qemu.
> > >> However, gdb could not establish a connection to qemu and produced the
> > following error:
> > >> /tmp/rtems/riscv❯ riscv-rtems6-gdb ticker.exe GNU gdb (GDB)
> > >> 10.1.90.20210125-git [..]
> > >>
> > >> For help, type "help".
> > >> Type "apropos word" to search for commands related to "word"...
> > >> Reading symbols from
> > /tools/modulesystem/tools/rtems/rtems6/install/bsps/riscv-
> > rtems6/grv32imafdc-smp/testsuites/samples/ticker.exe...
> > >> (gdb) target remote :1234
> > >> Remote debugging using :1234
> > >> bfd requires flen 8, but target has flen 4
> > >
> > > griscv are Jiri's BSPs and should run on sis and be able to be
> debugged that
> > way.
> > >
> > > He should know if they worked on qemu and he was able to connect gdb.
> > >
> >
> > Sorry for the confusion. Jiri already told me previously that for
> running on
> > qemu I need to use the BSPs without a "g" like rv32imafdc.
> > That's what I did for my test application. For testing with ticker.exe I
> chose
> > the wrong directory.
> > To clarify, I use the rv32imafdc BSP to run on qemu.
> > The application runs fine, but debugging it through the qemu gdb-server
> > does not work.
> > This does also happen with the ticker.exe of the rv32imafdc BSP.
> >
> > Best regards,
> >
> >     Jan
> >
> > > Otherwise, this looks like a potential mismatch of 32 and 64 bit stuff
> > > like gdb wasn't built with both 32 and 64 bit riscv support. Which
> > > seems odd to me because it lives in the same repo as binutils and
> > > should have a comparable build of binutils.
> > >
> > >
> > >> The tools and rtems are built from master a couple of days ago.
> > >> I used the following command line for qemu (v. 4.2.0):
> > >> qemu-system-riscv32 -nographic -machine virt -m 2G -nographic -net
> > >> none -serial mon:stdio -bios /tmp/riscv/ticker.exe -s -S
> > >>
> > >> Does anyone have a hint if the problem is with qemu, gdb or rtems?
> > >> Without gdb the program runs normally in qemu.
> > >>
> > >> Best regards,
> > >>
> > >>     Jan
> > >>
> > >> Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) German
> > >> Aerospace Center Institute for Software Technology | Software for
> > >> Space Systems and Interactive Visualization | Lilienthalplatz 7 |
> > >> 38108 Braunschweig | Germany
> > >>
> > >> Jan Sommer
> > >
> > > _______________________________________________
> > users mailing list
> > users at rtems.org
> > http://lists.rtems.org/mailman/listinfo/users
> >
> > _______________________________________________
> > users mailing list
> > users at rtems.org
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>
>
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