RE: [EXTERNAL] Re: [PATCH] Drivers: hv: vmbus: Improve the logc of reserving fb_mmio on Gen2 VMs

[Dexuan Cui]

> From: kernel test robot <l...@intel.com>
> Sent: Thursday, April 30, 2026 9:33 AM
> ...
> config: i386-buildonly-randconfig-002-20260430
>  ...
> All warnings (new ones prefixed by >>):
> 
> >> drivers/hv/vmbus_drv.c:2403:40: warning: result of comparison of constant
> 4294967296 with expression of type 'resource_size_t' (aka 'unsigned int') is
> always false [-Wtautological-constant-out-of-range-compare]
>     2403 |                         if (!low_mmio_base || low_mmio_base >= 
> SZ_4G ||
>          |                                               ~~~~~~~~~~~~~ ^  
> ~~~~~
>    1 warning generated.

Thanks for reporting the warning with the i386 kernel config.
I don't know if there is any x86-32 users nowadays, but this warning can be
fixed by:

-       if (!low_mmio_base || low_mmio_base >= SZ_4G ||
+       if (!low_mmio_base || upper_32_bits(low_mmio_base) ||
            (start && start < low_mmio_base)) {
                pr_warn("Unexpected low mmio base 0x%pa\n", &low_mmio_base);
        }