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Subject: RE: [PATCH v11 1/1] vfio/nvgpu: Add vfio pci variant module for grace
 hopper
Thread-Topic: [PATCH v11 1/1] vfio/nvgpu: Add vfio pci variant module for
 grace hopper
Thread-Index: AQHZ+VwgDWGk0VCFcUeltplt5s48drBCtrFA
Date:   Tue, 10 Oct 2023 08:42:13 +0000
Message-ID: <BN9PR11MB52762EE10CBBDF8AB98A53788CCDA@BN9PR11MB5276.namprd11.prod.outlook.com>
References: <20231007202254.30385-1-ankita@nvidia.com>
In-Reply-To: <20231007202254.30385-1-ankita@nvidia.com>
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> From: ankita@nvidia.com <ankita@nvidia.com>
> Sent: Sunday, October 8, 2023 4:23 AM
>=20
> PCI BAR are aligned to the power-of-2, but the actual memory on the
> device may not. A read or write access to the physical address from the
> last device PFN up to the next power-of-2 aligned physical address
> results in reading ~0 and dropped writes.
>=20

my question to v10 was not answered. posted again:
--
Though the variant driver emulates the access to the offset beyond
the available memory size, how does the userspace driver or the guest
learn to know the actual size and avoid using the invalid hole to hold
valid data?