openjdk 20 crash on linux kernel 5.19, because it can not support huge VM?

Ludovic Henry ludovic at rivosinc.com
Wed Nov 23 23:25:19 UTC 2022


Hi,

We are currently working on contributing to Qemu a command-line option to
disable/enable certain modes in Qemu. I'll keep you posted as soon as I've
anything material to share.

The solution on the OpenJDK should IMO to probe at startup for the satp
mode (sv39/sv48/sv57/sv64) and generate the appropriate and cheapest
movptr according to this value. I wouldn't want to pay the full cost of
sv57 or sv64 while no existing boards or hardware even support anything
more than sv48. Especially given the current discussions in RISC-V on
reducing the cost of auipc/jalr, movptr, and trampolines.

Thanks,
Ludovic

On Wed, Nov 23, 2022 at 9:33 AM Vladimir Kempik <vladimir.kempik at gmail.com>
wrote:

> Hello
>
> A kind of workaround for this case
>
> disable sv57 csr and rebuild qemu -
> https://github.com/qemu/qemu/blob/master/target/riscv/csr.c#L1027 put 0
> here
>
> Regards, Vladimir
>
> 23 нояб. 2022 г., в 04:08, Zixian Cai <zixian.cai at anu.edu.au> написал(а):
>
> This has been discussed in a previous thread.
> https://mail.openjdk.org/pipermail/riscv-port-dev/2022-September/000636.html
>
> I agree that it would be nice to support different modes. Although with
> the patches in QEMU/Kernel that can restrict the OS to run with sv39/sv48
> only, and the fact that there are not enough real hardware board supporting
> above sv48, I don’t know whether there will be sufficient motivation to fix
> the problem in the short term.
>
> Also worth noting until very recently (Intel implemented 5-level paging
> around the release of Ice Lake), x86_64 has been staying 48 bits a for long
> time.
>
> Sincerely,
> Zixian
>
>
> On 23/11/2022, 11:58, "riscv-port-dev" <riscv-port-dev-retn at openjdk.org>
> wrote:
>
> hi,
>    openjdk 20 crash on linux kernel 5.19, because it can not support huge
> VM?
>
> but I think openjdk as a application, it should not has any limitation on
> virtual address length,
>
> even if it has very close relationship with hardware, just as qemu should
> not depend on hardware VM size, it's none of business for an application,
> because all other apps can run very well.
>
> when will it support the newest kernel and qemu?
>
> https://groups.google.com/a/groups.riscv.org/g/sw-dev/c/pILY0WGHhOs
>
>
>
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