[PATCH v5 0/3] Add riscv semihosting support in u-boot

[Kautuk Consul]

Hi Leo,

What Qemu version are you using.
Can you please try with QEMU 7.1 or later ?
There is a fix which was merged after 7.0.

Thanks.

On Fri, Dec 2, 2022 at 2:16 PM Leo Liang <ycliang at andestech.com> wrote:

> Hi Kautuk,
>
> Sorry for the late reply.
> The CI failure still exists and
> if tested on QEMU(7.0.0) without a gdb attached,
> it is possible that we get weird output on console.[1]
>
> Another thing is that with your patch,
> QEMU could not exit with Ctrl a + x.
> This might be the reason for CI failure (timeout).
> Could you take a look at this?
>
> Yet with a gdb attached, everything works as expected,
> So maybe we could disable semihosting as default?
>
> Best regards,
> Leo
>
> [1] The weird console output looks like below,
> it outputs random character without us typing anything.
>
> U-Boot 2022.10-rc5 (Dec 02 2022 - 16:27:43 +0800)
> CPU:   rv64imafdcsuh
> Model: riscv-virtio,qemu
> DRAM:  2 GiB
> Core:  35 devices, 15 uclasses, devicetree: board
> Flash: 32 MiB
> Loading Environment from nowhere... OK
> In:    serial_semihosting
> Out:   serial_semihosting
> Err:   serial_semihosting
> Net:   eth0: virtio-net#1
> Hit any key to stop autoboot:  0
> =>
> 55555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555
> 55555555555555555555555555555555555555555555555555555555555555555555
>
>
>
> On Tue, Nov 29, 2022 at 12:27:51PM +0530, Kautuk Consul wrote:
> > I have tested it both on Qemu and Ventana's internal simulator.
> >
> > On Tue, Nov 29, 2022 at 12:06 PM Bin Meng <bmeng.cn at gmail.com> wrote:
> >
> > > Hi Kautuk,
> > >
> > > On Tue, Nov 29, 2022 at 2:29 PM Kautuk Consul <
> kconsul at ventanamicro.com>
> > > wrote:
> > > >
> > > > Hi,
> > > >
> > > > Can someone pick this patchset up ?
> > > >
> > > > It has been reviewed and there has been no comment on this in recent
> > > days.
> > > >
> > > > Thanks.
> > > >
> > > > On Fri, Sep 23, 2022 at 12:33 PM Kautuk Consul <
> kconsul at ventanamicro.com>
> > > wrote:
> > > >>
> > > >> Semihosting is a mechanism that enables code running on
> > > >> a target to communicate and use the Input/Output
> > > >> facilities on a host computer that is running a debugger.
> > > >> This patchset adds support for semihosting in u-boot
> > > >> for RISCV64 targets.
> > > >>
> > > >> CHANGES since v4:
> > > >> -       Check arch dependencies for SEMIHOSTING as well as
> > > SPL_SEMIHOSTING
> > > >>         config options as per Sean's comment.
> > > >> -       arch/riscv/lib/interrupts.c: Check for post and pre
> instructions
> > > >>         of the ebreak statement whether they are as per the RISCV
> > > >>         semihosting specification. Only then do a
> disable_semihosting
> > > >>         and epc += 4 and return.
> > > >>
> > > >> Compilation and test commands for SPL and S-mode configurations
> > > >> =================================================================
> > > >>
> > > >> U-Boot S-mode on QEMU virt
> > > >> ----------------------------
> > > >> // Compilation of S-mode u-boot
> > > >> ARCH=riscv
> > > >> CROSS_COMPILE=riscv64-unknown-linux-gnu-
> > > >> make qemu-riscv64_smode_defconfig
> > > >> make
> > > >> // Run riscv 64-bit u-boot with opensbi on qemu
> > > >> qemu-system-riscv64 -M virt -m 256M -display none -serial stdio
> -bios\
> > > >> opensbi/build/platform/generic/firmware/fw_jump.bin -kernel\
> > > >> u-boot/u-boot.bin
> > > >>
> > > >> U-Boot SPL on QEMU virt
> > > >> ------------------------
> > > >> // Compilation of u-boot-spl
> > > >> ARCH=riscv
> > > >> CROSS_COMPILE=riscv64-unknown-linux-gnu-
> > > >> make qemu-riscv64_spl_defconfig
> > > >> make OPENSBI=opensbi/build/platform/generic/firmware/fw_dynamic.bin
> > > >> // Run 64-bit u-boot-spl in qemu
> > > >> qemu-system-riscv64 -M virt -m 256M -display none -serial stdio
> -bios\
> > > >> u-boot/spl/u-boot-spl.bin -device\
> > > >> loader,file=u-boot/u-boot.itb,addr=0x80200000
> > > >>
> > >
> > > Do you have instructions on how to actually test semihosting? Does it
> > > require a JTAG debugger? But I see you are using QEMU?
> > >
> > > Regards,
> > > Bin
> > >
>