Re: [meta-arago][scarthgap][PATCH] linux-libc-headers: add DMA_HEAP_IOCTL_EXPORT uapi patch

Thu, 27 Aug 2026 10:38:36 -0700 


On 8/27/2026 10:21 PM, Andrew Davis wrote:
> On 8/27/26 10:07 AM, Hari Prasath via lists.yoctoproject.org wrote:
>> Copy the TI vendor kernel dma-heap.h header, which has the
>> DMA_HEAP_IOCTL_EXPORT ioctl that the default linux-libc-headers
>> doesn't have.
>>
>> Signed-off-by: Hari Prasath Gujulan Elango <[email protected]>
>> ---
> 
> https://github.com/openembedded/openembedded-core/blob/master/meta/
> recipes-kernel/linux-libc-headers/linux-libc-headers.inc#L7

That is usual problem with when uapi is getting updated
https://github.com/TexasInstruments/ti-linux-kernel/blob/ti-linux-6.18.y/include/uapi/linux/dma-heap.h#L78


Now SW stack using this ioctl will fail to compile in case of
1- using include from rootfs or
2- compiling on target itself

recommendation is understood,

thanks for suggesting alternative way out

> 
>>   .../0001-dma-heap-add-export-ioctl.patch      | 58 +++++++++++++++++++
>>   .../linux-libc-headers_%.bbappend             | 10 ++++
>>   2 files changed, 68 insertions(+)
>>   create mode 100644 meta-arago-distro/recipes-kernel/linux-libc-
>> headers/linux-libc-headers/0001-dma-heap-add-export-ioctl.patch
>>   create mode 100644 meta-arago-distro/recipes-kernel/linux-libc-
>> headers/linux-libc-headers_%.bbappend
>>
>> diff --git a/meta-arago-distro/recipes-kernel/linux-libc-headers/
>> linux-libc-headers/0001-dma-heap-add-export-ioctl.patch b/meta-arago-
>> distro/recipes-kernel/linux-libc-headers/linux-libc-headers/0001-dma-
>> heap-add-export-ioctl.patch
>> new file mode 100644
>> index 00000000..e96c9ff0
>> --- /dev/null
>> +++ b/meta-arago-distro/recipes-kernel/linux-libc-headers/linux-libc-
>> headers/0001-dma-heap-add-export-ioctl.patch
>> @@ -0,0 +1,58 @@
>> +From: Andrew Davis <[email protected]>
>> +Subject: [PATCH] dma-buf: heaps: expose DMA_HEAP_IOCTL_EXPORT uapi
>> +
>> +Mirrors ti-linux-kernel commit 8715cc31cfe8a191ade660ff787fedbadcb187d4
>> +("TI: HACK: dma-buf: heaps: Add Heap export from offset IOCTL"), limited
>> +to the include/uapi/linux/dma-heap.h hunk. The kernel already ships this
>> +ioctl; linux-libc-headers fetches its own independent pristine tarball
>> +and knows nothing about it, so userspace can't see the symbol without
>> +this patch.
>> +
>> +Upstream-Status: Inappropriate [TI kernel hack, not upstream]
>> +Signed-off-by: Andrew Davis <[email protected]>
>> +Signed-off-by: Udit Kumar <[email protected]>
>> +
>> +diff --git a/include/uapi/linux/dma-heap.h b/include/uapi/linux/dma-
>> heap.h
>> +index a4cf716a49fa6..db749800b6c16 100644
>> +--- a/include/uapi/linux/dma-heap.h
>> ++++ b/include/uapi/linux/dma-heap.h
>> +@@ -39,6 +39,25 @@ struct dma_heap_allocation_data {
>> +     __u64 heap_flags;
>> + };
>> +
>> ++/**
>> ++ * struct dma_heap_export_data - metadata passed from userspace for
>> export
>> ++ * @offset:        offset from heap base
>> ++ * @len:        size of the allocation
>> ++ * @fd:            will be populated with a fd which provides the
>> ++ *            handle to the allocated dma-buf
>> ++ * @fd_flags:        file descriptor flags used when allocating
>> ++ * @heap_flags:        flags passed to heap
>> ++ *
>> ++ * Provided by userspace as an argument to the ioctl
>> ++ */
>> ++struct dma_heap_export_data {
>> ++    __u64 offset;
>> ++    __u64 len;
>> ++    __u32 fd;
>> ++    __u32 fd_flags;
>> ++    __u64 heap_flags;
>> ++};
>> ++
>> + #define DMA_HEAP_IOC_MAGIC        'H'
>> +
>> + /**
>> +@@ -50,4 +69,13 @@ struct dma_heap_allocation_data {
>> + #define DMA_HEAP_IOCTL_ALLOC    _IOWR(DMA_HEAP_IOC_MAGIC, 0x0,\
>> +                       struct dma_heap_allocation_data)
>> +
>> ++/**
>> ++ * DOC: DMA_HEAP_IOCTL_EXPORT - allocate memory at offset
>> ++ *
>> ++ * Takes a dma_heap_export_data struct and returns it with the fd field
>> ++ * populated with the dmabuf handle of the export.
>> ++ */
>> ++#define DMA_HEAP_IOCTL_EXPORT    _IOWR(DMA_HEAP_IOC_MAGIC, 0x1,\
>> ++                      struct dma_heap_export_data)
>> ++
>> + #endif /* _UAPI_LINUX_DMABUF_POOL_H */
>> diff --git a/meta-arago-distro/recipes-kernel/linux-libc-headers/
>> linux-libc-headers_%.bbappend b/meta-arago-distro/recipes-kernel/
>> linux-libc-headers/linux-libc-headers_%.bbappend
>> new file mode 100644
>> index 00000000..7f0345ab
>> --- /dev/null
>> +++ b/meta-arago-distro/recipes-kernel/linux-libc-headers/linux-libc-
>> headers_%.bbappend
>> @@ -0,0 +1,10 @@
>> +# linux-libc-headers fetches its own pristine kernel.org tarball,
>> independent
>> +# of ti-linux-kernel, so it doesn't see TI's out-of-tree dma-heap
>> ioctl even
>> +# though the running kernel already has it. This carries a minimal,
>> purely
>> +# additive patch (no existing symbols touched) so that ioctl is
>> visible to
>> +# userspace via /usr/include/linux/dma-heap.h without re-sourcing the
>> whole
>> +# recipe from our kernel tree.
>> +
>> +FILESEXTRAPATHS:prepend := "${THISDIR}/${BPN}:"
>> +
>> +SRC_URI += "file://0001-dma-heap-add-export-ioctl.patch"
> 



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