[Mesa-dev] [PATCH] anv: Limit VkDeviceMemory objects to 2GB

[Ilia Mirkin]

On Tue, Apr 11, 2017 at 1:58 PM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> Cc: "Juan A. Suárez" <jasuarez at igalia.com>
> ---
>  src/intel/vulkan/anv_device.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
>
> diff --git a/src/intel/vulkan/anv_device.c b/src/intel/vulkan/anv_device.c
> index 35ef4c4..b24c739 100644
> --- a/src/intel/vulkan/anv_device.c
> +++ b/src/intel/vulkan/anv_device.c
> @@ -1539,6 +1539,23 @@ VkResult anv_AllocateMemory(
>     assert(pAllocateInfo->memoryTypeIndex == 0 ||
>            (!device->info.has_llc && pAllocateInfo->memoryTypeIndex < 2));
>
> +   /* The kernel relocation API has a limitation of a 32-bit delta value
> +    * applied to the address before it is written which, in spite of it being
> +    * unsigned, is treated as signed .  Because of the way that this maps to
> +    * the Vulkan API, we cannot handle an offset into a buffer that does not
> +    * fit into a signed 31 bits.  The only mechanism we have for dealing with

32 bits?

> +    * this at the moment is to limit all VkDeviceMemory objects to a maximum
> +    * of 2GB each.  The Vulkan spec allows us to do this:
> +    *
> +    *    "Some platforms may have a limit on the maximum size of a single
> +    *    allocation. For example, certain systems may fail to create
> +    *    allocations with a size greater than or equal to 4GB. Such a limit is
> +    *    implementation-dependent, and if such a failure occurs then the error
> +    *    VK_ERROR_OUT_OF_DEVICE_MEMORY should be returned."
> +    */
> +   if (pAllocationInfo->allocationSize > (1ull << 31))

1<<31 is not representable in a 32-bit signed int. did you mean >= ?

> +      return VK_ERROR_OUT_OF_HOST_MEMORY;

The comment above would suggest OUT_OF_DEVICE_MEMORY...

> +
>     /* FINISHME: Fail if allocation request exceeds heap size. */
>
>     mem = vk_alloc2(&device->alloc, pAllocator, sizeof(*mem), 8,
> --
> 2.5.0.400.gff86faf
>
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