Error when build a 32bit linux kernel with riscv32-linux-gnu on 32bit OS

[Haoran Shi]

Help!!! Has anyone build the linux kernel successfully with riscv32-unknown-linux-gnu tools? 

I downloaded the linux kernel according to the instructions in https://github.com/riscv/riscv-linux and checkout to the branch priv-1.9.

And the riscv32-unknown-linux-gnu tools is from https://github.com/riscv/riscv-tools with xlen=32.

But Whatever I configure the linux kernel compiler environment, I always met errors.

After "$ make defconfig" "$ make menuconfig", I also

changed Platform type -> CPU selection from Rocket to Generic RISC-V
changed Kernel type -> Kernel code model from 64-bit kernel to 32-bit kernel
changed General setup -> Cross-compiler tool prefix from riscv64-unknown-linux-gnu- to riscv32-unknown-linux-gnu- (which I built in riscv-tools)

but I got an error that 

```

include/asm-generic/div64.h:224:22: error: passing argument 1 of '__div64_32' from incompatible pointer type [-Werror=incompatible-pointer-types]

   __rem = __div64_32(&(n), __base); \

                      ^

```

The OS on my computer is

```

Linux ubuntu32 4.4.0-31-generic #50~14.04.1-Ubuntu SMP Wed Jul 13 01:06:37 UTC 2016 i686 i686 i686 GNU/Linux

```

I have no idea how to fix it...Could anyone help me? Thanks a lot!

[Sijmen Woutersen]

Hi,

We made some fixes and got 32-bit linux booting on our own core, see: https://github.com/Technolution/riscv-linux/tree/priv-1.9.

Notably;

https://github.com/riscv/riscv-linux/commit/d47ccdce841df25b64424350eb200fc5df222148

https://github.com/riscv/riscv-linux/commit/cf441b3721c0b781fedcbfedafc5724d7583dd96

We do intend to make a pull request at some point, but we have to isolate some changes & cleanup. The above patches disable / break floating point so you might not want everything.

Regards,

Sijmen

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Sijmen Woutersen  Architect

T +31(0)182594000 | M +31(0)615426154 | E sijmen.w...@technolution.nl 

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[Haoran Shi]

Thanks for your effort! I got a 32-bit vmlinux according to your solution, however, when I boot the kernel with bbl in qemu, it just reminds that ”cannot allocate memory" 

shore@ubuntu32:~/riscv-qemu$ ./riscv32-softmmu/qemu-system-riscv32 -nographic -kernel /home/shore/riscv/riscv32-unknown-elf/bin/bbl -drive file=/home/shore/linux-4.6.2/root.bin,format=raw -m 512M
qemu-system-riscv32: cannot set up guest memory 'riscv_spike_board.ram': Cannot allocate memory

Actually, the memory of my machine is 4GB. I cannot believe that it is because the memory is not adequate. I mean that the 32bit OS can access 4GB memory at most, the OS of my computer is

Linux ubuntu32 4.4.0-31-generic #50~14.04.1-Ubuntu SMP Wed Jul 13 01:06:37 UTC 2016 i686 i686 i686 GNU/Linux

Actually, the bbl is built according to https://github.com/riscv/riscv-pk/tree/master, except that I modify the configuration because I am running a 32bit Machine

../configure --prefix=$RISCV --host=riscv32-unknown-linux-gnu --enable-32bit --with-payload=/home/shore/linux-4.6.2/vmlinux

the drive file system is build according to the https://github.com/riscv/riscv-tools#creating-root-disk

Have you met such probloms or do you have any solution?

Maybe I should open a new thread to ask this problem?

 在 2016年11月29日星期二 UTC+8上午2:12:45，Sijmen Woutersen写道：

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Sijmen Woutersen  Architect

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[Haoran Shi]

The solution is described here, https://github.com/riscv/riscv-qemu/issues/39.

Thanks for all the kindness!

在 2016年11月25日星期五 UTC+8下午10:58:56，Haoran Shi写道：