axidma: axidma_chrdev.c: axidma_mmap: 294: Unable to allocate contiguous DMA memory region of size 8294400.

[L123ee]

When i test. " axidma-benchmark" application, print this error:
"""
AXI DMA Benchmark Parameters:
Transmit Buffer Size: 7.91 Mb
Receive Buffer Size: 7.91 Mb
vma->vm_start = 0xb6659000
dma_alloc->user_addr = b6659000
dma_alloc->dma_addr=0x72612d78
vma->vm_page_prot = 0x71f

    Number of DMA Transfers: 1000 transfers

axidma axidma: coherent DMA mask is unset
dma_alloc->size = 0x007e9000
axidma: axidma_chrdev.c: axidma_mmap: 294: Unable to allocate contiguous DMA memory region of size 8294400.
axidma: axidma_chrdev.c: axidma_mmap: 296: Please make sure that you specified cma= on the kernel command line, and the size is large enough.
Unable to allocate transmit buffer from the AXI DMA device.: Cannot allocate memory
"""

root@axidma_7045:/# cat /proc/meminfo
MemTotal:        1030296 kB
MemFree:          998232 kB
MemAvailable:     988188 kB
Buffers:               0 kB
Cached:            15516 kB
SwapCached:            0 kB
Active:             9404 kB
Inactive:           8392 kB
Active(anon):       9404 kB
Inactive(anon):     8392 kB
Active(file):          0 kB
Inactive(file):        0 kB
Unevictable:           0 kB
Mlocked:               0 kB
HighTotal:        262144 kB
HighFree:         242904 kB
LowTotal:         768152 kB
LowFree:          755328 kB
SwapTotal:             0 kB
SwapFree:              0 kB
Dirty:                 0 kB
Writeback:             0 kB
AnonPages:          2324 kB
Mapped:             4768 kB
Shmem:             15516 kB
Slab:               9860 kB
SReclaimable:       6200 kB
SUnreclaim:         3660 kB
KernelStack:         384 kB
PageTables:          192 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:      515148 kB
Committed_AS:      30796 kB
VmallocTotal:     245760 kB
VmallocUsed:           0 kB
VmallocChunk:          0 kB
CmaTotal:          32768 kB
CmaFree:           32436 kB
root@axidma_7045:/# dmesg | grep cma
cma: early_cma(32M)
cma: dma_contiguous_reserve(limit ffffffff)
cma: dma_contiguous_reserve: reserving 32 MiB for global area
cma: cma_declare_contiguous(size 0x02000000, base 0x00000000, limit 0xffffffff alignment 0x00000000)
cma: Reserved 32 MiB at 0x3e000000
Kernel command line: console=ttyPS0,115200 earlyprintk cma=32M
Memory: 990548K/1048576K available (6144K kernel code, 238K rwdata, 1568K rodata, 1024K init, 154K bss, 25260K reserved, 32768K cma-reserved, 229376K highmem)
cma: cma_alloc(cma c0a4d0e0, count 64, align 6)
cma: cma_alloc(): returned effb8000
cma: cma_alloc(cma c0a4d0e0, count 1, align 0)
cma: cma_alloc(): returned effb8800
cma: cma_alloc(cma c0a4d0e0, count 8, align 3)
cma: cma_alloc(): returned effb8900
cma: cma_alloc(cma c0a4d0e0, count 1, align 0)
cma: cma_alloc(): returned effb8820
cma: cma_alloc(cma c0a4d0e0, count 8, align 3)
cma: cma_alloc(): returned effb8a00
cma: cma_alloc(cma c0a4d0e0, count 1, align 0)
cma: cma_alloc(): returned effb8840
axidma: axidma_chrdev.c: axidma_mmap: 296: Please make sure that you specified cma=<size> on the kernel command line, and the size is large enough.
axidma: axidma_chrdev.c: axidma_mmap: 296: Please make sure that you specified cma=<size> on the kernel command line, and the size is large enough.
axidma: axidma_chrdev.c: axidma_mmap: 296: Please make sure that you specified cma=<size> on the kernel command line, and the size is large enough.
axidma: axidma_chrdev.c: axidma_mmap: 296: Please make sure that you specified cma=<size> on the kernel command line, and the size is large enough.
axidma: axidma_chrdev.c: axidma_mmap: 296: Please make sure that you specified cma=<size> on the kernel command line, and the size is large enough.

32M of CMA memory has been configured in the kernel。

what may be the above problem and how to solve it?

[hanie-gh]

You can increase the CMA size in the Linux kernel with the following bootargs in your device tree:
chosen { setenv bootargs " earlycon console=ttyPS1,115200 clk_ignore_unused root=/dev/ram0 rw init_fatal_sh=1 cma=1200M" };

[wangzhenhua92429]

你发给我的邮件已收到！                                ——王振华

[Yuxin-Yu]

hi @L123ee .Have you solved this problem? My CMA capacity is 256MB and I also get the same error

root@debian:/proc# dmesg | grep cma
[    0.000000] cma: Reserved 256 MiB at 0x00000000f0000000
[    0.000000] Memory: 3774496K/4192256K available (7046K kernel code, 4956K rwdata, 4096K rodata, 2158K init, 316K bss, 155616K reserved, 262144K cma-reserved)
[ 1545.942406] axidma: axidma_chrdev.c: axidma_mmap: 283: Please make sure that you specified cma=<size> on the kernel command line, and the size is large enough.
[ 1549.318456] axidma: axidma_chrdev.c: axidma_mmap: 283: Please make sure that you specified cma=<size> on the kernel command line, and the size is large enough.