Re: [XEN][PATCH v12 20/20] tools/xl: Add new xl command overlay for device tree overlay support

[Michal Orzel <michal.orzel@amd.com>]

On 06/09/2023 08:55, Jan Beulich wrote:
> 
> 
> On 06.09.2023 03:16, Vikram Garhwal wrote:
>> --- a/tools/xl/xl_vmcontrol.c
>> +++ b/tools/xl/xl_vmcontrol.c
>> @@ -1265,6 +1265,58 @@ int main_create(int argc, char **argv)
>>      return 0;
>>  }
>>
>> +int main_dt_overlay(int argc, char **argv)
>> +{
>> +    const char *overlay_ops = NULL;
>> +    const char *overlay_config_file = NULL;
>> +    void *overlay_dtb = NULL;
>> +    int rc;
>> +    uint8_t op;
>> +    int overlay_dtb_size = 0;
>> +    const int overlay_add_op = 1;
>> +    const int overlay_remove_op = 2;
>> +
>> +    if (argc < 2) {
>> +        help("dt_overlay");
>> +        return EXIT_FAILURE;
>> +    }
>> +
>> +    overlay_ops = argv[1];
>> +    overlay_config_file = argv[2];
>> +
>> +    if (strcmp(overlay_ops, "add") == 0)
>> +        op = overlay_add_op;
>> +    else if (strcmp(overlay_ops, "remove") == 0)
>> +        op = overlay_remove_op;
>> +    else {
>> +        fprintf(stderr, "Invalid dt overlay operation\n");
>> +        return EXIT_FAILURE;
>> +    }
>> +
>> +    if (overlay_config_file) {
>> +        rc = libxl_read_file_contents(ctx, overlay_config_file,
>> +                                      &overlay_dtb, &overlay_dtb_size);
>> +
>> +        if (rc) {
>> +            fprintf(stderr, "failed to read the overlay device tree file %s\n",
>> +                    overlay_config_file);
>> +            free(overlay_dtb);
>> +            return ERROR_FAIL;
>> +        }
>> +    } else {
>> +        fprintf(stderr, "overlay dtbo file not provided\n");
>> +        return ERROR_FAIL;
>> +    }
>> +
>> +    rc = libxl_dt_overlay(ctx, overlay_dtb, overlay_dtb_size, op);
> 
> Because of this being Arm-only (as validly pointed out by osstest), I expect
> the entire function here as well as its entry in cmd_table[] want to be
> Arm-specific, too? Of course it would be nice to not key this to __arm__ /
> __aarch64__, but to something that would not need touching again if the
> underlying infrastructure was made available to, say, RISC-V as well. But of
> course - right now the goal needs to be to address the CI and osstest
> breakage.
I agree. I would suggest to guard it with LIBXL_HAVE_DT_OVERLAY which is for now
only defined for arm32/arm64. This way the code will not need to be modified if other
arch gain support for the feature.
If you agree, I can send a patch to unbreak CI unless you want to do this.

~Michal