Re: [Qemu-devel] [Qemu-riscv] RISCV: when will the CLIC be ready?

[liuzhiwei <zhiwei_liu@c-sky.com>]

On 2019/8/20 上午12:38, Chih-Min Chao wrote:
>
>
> On Mon, Aug 19, 2019 at 9:47 PM liuzhiwei <zhiwei_liu@c-sky.com 
> <mailto:zhiwei_liu@c-sky.com>> wrote:
>
>
>     On 2019/8/17 上午1:29, Alistair Francis wrote:
>     > On Thu, Aug 15, 2019 at 8:39 PM liuzhiwei<zhiwei_liu@c-sky.com
>     <mailto:zhiwei_liu@c-sky.com>> wrote:
>     >> Hi, Palmer
>     >>
>     >> When Michael Clark still was the maintainer of RISCV QEMU, he
>     wrote in the mail list, "the CLIC interrupt controller is under
>     testing,
>     >> and will be included in QEMU 3.1 or 3.2". It is pity that the
>     CLIC is not in
>     >> included even in QEMU 4.1.0.
>     > I see that there is a CLIC branch available here:
>     > https://github.com/riscv/riscv-qemu/pull/157
>     >
>     > It looks like all of the work is in a single commit
>     >
>     (https://github.com/riscv/riscv-qemu/pull/157/commits/206d9ac339feb9ef2c325402a00f0f45f453d019)
>     > and that most of the other commits in the PR have already made
>     it into
>     > master.
>     >
>     > Although the CLIC commit is very large it doesn't seem impossible to
>     > manually pull out the CLIC bits and apply it onto master.
>     >
>     > Do you know the state of the CLIC model? If it's working it
>     shouldn't
>     > be too hard to rebase the work and get the code into mainline.
>     >
>     > Alistair
>     >
>     Hi,  Alistair
>
>     In my opinion, the CLIC code almost works.
>
>     Last year when my workmate ported an RTOS, I once read the CLIC
>     specification and used the CLIC model code. It worked through  all
>     the tests after fixed two bugs. I also had sent the patch to
>     Michael, but without response(maybe a wrong email address).
>
>     diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
>     index 7bf6cbc..95d80ab 100644
>     --- a/target/riscv/cpu_helper.c
>     +++ b/target/riscv/cpu_helper.c
>     @@ -505,6 +505,9 @@ static target_ulong
>     riscv_intr_pc(CPURISCVState *env,
>           if (!(async || clic)) {
>               return tvec & ~0b11;
>           }
>     +    if (clic) {
>     +        cause &= 0x3ff;
>     +    }
>
>           /* bits [1:0] encode mode; 0 = direct, 1 = vectored, 2 >=
>     reserved */
>           switch (mode1) {
>     @@ -645,6 +648,9 @@ void riscv_cpu_do_interrupt(CPUState *cs)
>               riscv_cpu_set_mode(env, PRV_M);
>           }
>
>     +    if (clic) {
>     +        env->exccode = 0;
>     +    }
>           /* NOTE: it is not necessary to yield load reservations
>     here. It is only
>              necessary for an SC from "another hart" to cause a load
>     reservation
>              to be yielded. Refer to the memory consistency model
>     section of the
>
>     After that, the specification has updated and the code may
>     changed. I didn't pull new code again.
>
>     If the CLIC model may merged into the mainline, and no body
>     maintain the code, I'd like to work on it, fixing the bugs and
>     updating the code according to latest specification.
>
>     Best Regards,
>     Zhiwei
>
>     >> As we have cpus using CLIC, I have to use the out of tree qemu
>     code in SIFIVE
>     >> a long time. Could you tell me when it will be upstreamed?
>     >>
>     >> Best Regards
>     >> Zhiwei
>     >>
>
>
> Hi Zhiwei,
>
> I think what Alistair point out is the latest clic version (or 
> https://github.com/riscv/riscv-qemu/tree/riscv-qemu-3.1). The two 
> versions, on pull request and 3.1 branch, should be similar.
> As far as I know, there is no concrete plan on CLIC patch in short term.
> It is good to know that the clic patch has been run with real RTOS.
> It is also great if you could update the implementation to latest spec 
> and send the patch again.
>
> chihmin

Hi chihmin,

Thanks for your reminding and approval. I will pull the latest clic 
version code and send the patch about two or three weeks later.

The RTOS is Rhino,  which is the kernel of 
AliOS-Things(https://github.com/alibaba/AliOS-Things).

It is also the kernel of YOC(https://cop.c-sky.com).

Best Regards
Zhiwei