This repository provides kernel module to easily create or delete u-dma-buf.
Once this device driver is loaded into your system, you will be able to access /dev/u-dma-buf-mgr.
u-dma-buf can be created/deleted by writing the command to /dev/u-dma-buf-mgr as a string.
Udmabuf is a Linux device driver that allocates contiguous memory blocks in the kernel space as DMA buffers and makes them available from the user space.
For details of udmabuf, please refer to following URL.
https://github.com/ikwzm/udmabuf
shell$ sudo sh -c "echo 'create udmabuf8 0x10000' > /dev/u-dma-buf-mgr"
[16463.308265] u-dma-buf-mgr: create udmabuf8 size=65536
[16463.311147] u-dma-buf udmabuf8: driver version = 4.3.0
[16463.311148] u-dma-buf udmabuf8: major number = 238
[16463.311149] u-dma-buf udmabuf8: minor number = 0
[16463.311149] u-dma-buf udmabuf8: phys address = 0x000000007b410000
[16463.311150] u-dma-buf udmabuf8: buffer size = 65536
[16463.311150] u-dma-buf udmabuf8: dma device = u-dma-buf.1.auto
[16463.311151] u-dma-buf udmabuf8: dma bus = platform
[16463.311151] u-dma-buf udmabuf8: dma coherent = 1
[16463.311152] u-dma-buf udmabuf8: dma mask = 0x00000000ffffffff
[16463.311152] u-dma-buf u-dma-buf.1.auto: driver installed.shell$ sudo sh -c "echo 'create udmabuf9 0x10000 bus=pci device=0000:00:18.7' > /dev/u-dma-buf-mgr"
[18758.896248] u-dma-buf-mgr: create udmabuf9 size=65536
[18758.899611] u-dma-buf udmabuf0: driver version = 4.3.0
[18758.899612] u-dma-buf udmabuf0: major number = 238
[18758.899613] u-dma-buf udmabuf0: minor number = 0
[18758.899614] u-dma-buf udmabuf0: phys address = 0x000000007b410000
[18758.899614] u-dma-buf udmabuf0: buffer size = 65536
[18758.899615] u-dma-buf udmabuf0: dma device = 0000:00:18.7
[18758.899615] u-dma-buf udmabuf0: dma bus = pci
[18758.899626] u-dma-buf udmabuf0: dma coherent = 1
[18758.899628] u-dma-buf udmabuf0: dma mask = 0x00000000ffffffff
[18758.899628] u-dma-buf: driver installed.create <device-name> <size> [bus=<bus>] [device=<device>] [dma-mask=<dma-mask-size>]
The device-name argument is used to set the name of device.
The device-name argument is mandatory.
The size argument is used to set the capacity of DMA buffer in bytes.
The size argment is mandatory.
The device option specifies the parent device of u-dma-buf.
If the device option is omitted, it creates its own platform device.
The bus option specifies the bus to search for the device specified by the device option.
If the bus option is omitted, the platform bus is searched.
The dma-mask option specifies the number of bits in the dma mask value.
If the parent device is specified by the device option, the dma-mask option is ignored because the dma-mask set for the parent device takes precedence.
The quirk-mmap-on option specifies use u-dma-buf's own quirk mmap().
If this option is omitted, quirk-mmap-mode follows the u-dma-buf default.
The quirk-mmap-off option specifies u-dma-buf's own quirk mmap() is prohibited.
If this option is omitted, quirk-mmap-mode follows the u-dma-buf default.
The quirk-mmap-auto option specifies the automatically selects whether or not to use u-dma-buf's own quirk mmap().
If this option is omitted, quirk-mmap-mode follows the u-dma-buf default.
shell$ sudo sh -c "echo 'delete udmabuf8' > /dev/u-dma-buf-mgr"
[16528.506714] u-dma-buf-mgr: delete udmabuf8
[16528.508506] u-dma-buf u-dma-buf.1.auto: driver removed.delete <device-name>
The device-name argument is used to set the name of device.
The device-name argument is mandatory.
The device-name argument must be the device name created by the create command.
Before installing u-dma-buf-mgr, u-dma-buf must be installed beforehand.
Load the u-dma-buf-mgr using insmod.
shell$ sudo insmod u-dma-buf-mgr.koor load the u-dma-buf-mgr using modprobe.
shell$ sudo modprobe u-dma-buf-mgrThe module can be uninstalled by the rmmod command.
shell$ sudo rmmod u-dma-buf-mgrFor details, refer to the following URL.
This repository contains a Makefie. Makefile has the following Parameters:
| Parameter Name | Description | Default Value |
|---|---|---|
| ARCH | Architecture Name | $(shell uname -m | sed -e s/arm.*/arm/ -e s/aarch64.*/arm64/) |
| KERNEL_SRC | Kernel Source Directory | /lib/modules/$(shell uname -r)/build |
| KBUILD_EXTRA_SYMBOLS | u-dma-buf Module.symvers | none |
Symbol information of functions/variables exported by u-dma-buf is required to compile u-dma-buf-mgr. Therefore, either of the following two is required.
Set KBUILD_EXTRA_SYMBOLS variable to Module.symvers created by u-dma-buf
If you have a cross-compilation environment for target system, you can compile with:
shell$ make ARCH=arm KERNEL_SRC=/home/fpga/work/FPGA-SoC-Linux-Kernel-6.1/linux-6.1.33-armv7-fpga KBUILD_EXTRA_SYMBOLS=/home/fpga/work/udmabuf/Module.symvers
make -C /home/fpga/work/FPGA-SoC-Linux-Kernel-6.1/linux-6.1.33-armv7-fpga ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- M=/home/fpga/work/u-dma-buf-mgr CONFIG_U_DMA_BUF_MGR=m
make[1]: Entering directory '/home/fpga/work/FPGA-SoC-Linux-Kernel-6.1/linux-6.1.33-armv7-fpga'
CC [M] /home/fpga/work/u-dma-buf-mgr/u-dma-buf-mgr.o
MODPOST /home/fpga/work/u-dma-buf-mgr/Module.symvers
CC [M] /home/fpga/work/u-dma-buf-mgr/u-dma-buf-mgr.mod.o
LD [M] /home/fpga/work/u-dma-buf-mgr/u-dma-buf-mgr.ko
make[1]: Leaving directory '/home/fpga/work/FPGA-SoC-Linux-Kernel-6.1/linux-6.1.33-armv7-fpga'The ARCH variable specifies the architecture name.
The KERNEL_SRC variable specifies the Linux Kernel source code path.
The KBUILD_EXTRA_SYMBOLS variable sepcifies the u-dma-buf Module.symbers file.
If your target system is capable of self-compiling the Linux Kernel module, you can compile it with:
shell$ make KBUILD_EXTRA_SYMBOLS=/home/fpga/src/u-dma-buf/Module.symvers allYou need the kernel source code in /lib/modules/$(shell uname -r)/build to compile.
It can also be compiled into the Linux Kernel Source Tree.
shell$ mkdir <linux-source-tree>/drivers/staging/u-dma-buf-mgrshell$ cp Kconfig Makefile u-dma-buf.c <linux-source-tree>/drivers/staging/u-dma-buf-mgrshell$ diff <linux-source-tree>/drivers/staging/Kconfig
:
source "drivers/staging/u-dma-buf/Kconfig"
+source "drivers/staging/u-dma-buf-mgr/Kconfig"
+shell$ diff <linux-source-tree>/drivers/staging/Makefile
:
obj-$(CONFIG_U_DMA_BUF) += u-dma-buf/
+obj-$(CONFIG_U_DMA_BUF_MGR) += u-dma-buf-mgr/For make menuconfig, set the following:
Device Drivers --->
Staging drivers --->
<M> u-dma-buf(User space mappable DMA Buffer) --->--- u-dma-buf(User space mappable DMA Buffer)
<M> u-dma-buf-mgr(User space mappable DMA Buffer Manager)
```console
If you write it directly in defconfig:
```console
shell$ diff <linux-source-tree>/arch/arm64/configs/xilinx_zynqmp_defconfig
:
+CONFIG_U_DMA_BUF=m
+CONFIG_U_DMA_BUF_MGR=m
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