Re: [kvm-ppc-devel] [PATCH] Add print for PowerPC qemu for failed DCR read/writes

[Christian Ehrhardt <ehrhardt-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>]

hi Jerone,
I think this is good for debugging to find unsupported hardware, but it should not be enabled by default (you could get a printf storm if a guest workload does stupid things). Maybe qemu has some debug/verbose options you can use.
And additionally it would be useful for the dcr_write patch to print the value it tried to write.
I also don't know if we really need that caps-locked in the output.

Jerone Young wrote:
> # HG changeset patch
> # User Jerone Young <jyoung5-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
> # Date 1202249136 21600
> # Node ID 4bbbf98ebf05ef77dbb68e2131b3bc0764767c99
> # Parent  f8cab6a29bf3f34f1cbf4d1e6d7bd21809fd4184
> Add print for PowerPC qemu for failed DCR read/writes
> 
> This patch adds a print to notify of failed reads and rights. Currently
> we will still ignore them (until development is fully done). But this makes
> them easier to spot.
> 
> Signed-off-by: Jerone Young <jyoung5-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
> 
> diff --git a/qemu/qemu-kvm-powerpc.c b/qemu/qemu-kvm-powerpc.c
> --- a/qemu/qemu-kvm-powerpc.c
> +++ b/qemu/qemu-kvm-powerpc.c
> @@ -178,13 +178,17 @@ int handle_powerpc_dcr_read(int vcpu, ui
>  int handle_powerpc_dcr_read(int vcpu, uint32_t dcrn, uint32_t *data)
>  {
>      CPUState *env = cpu_single_env;
> -    ppc_dcr_read(env->dcr_env, dcrn, data);
> +    if (ppc_dcr_read(env->dcr_env, dcrn, data) < 0)
> +        printf("DCR FAILED on READ at 0x%x\n", dcrn);
> + 
>      return 0; /* XXX ignore failed DCR ops */
>  }
> 
>  int handle_powerpc_dcr_write(int vcpu, uint32_t dcrn, uint32_t data)
>  {
>      CPUState *env = cpu_single_env;
> -    ppc_dcr_write(env->dcr_env, dcrn, data);
> +    if (ppc_dcr_write(env->dcr_env, dcrn, data) < 0)
> +        printf("DCR FAILED on WRITE at 0x%x\n", dcrn);
just a suggestion

        printf("%s - failed writing 0x%x @ 0x%x\n", dcrn, data);

> +
>      return 0; /* XXX ignore failed DCR ops */
>  }
> 
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-- 

Grüsse / regards, 
Christian Ehrhardt
IBM Linux Technology Center, Open Virtualization

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