Hello, I am currently trying to allocate a bit more than 2 GB of buffer via the VIDIOC_REQBUFS ioctl of V4L2 on a Jetson Xavier working with L4T 31.1 Our image size is 566442562 = 48 211 968 Bytes and we need to allocate 36 buffers for our application. I noticed that the current maximum number of buffer is 32. The dmesg output is the following [ 330.080662] Unable to handle kernel NULL pointer dereference at virtual address 00000020 [ 330.088563] Mem abort info: [ 330.091547] ESR = 0x96000005 [ 330.094774] Exception class = DABT (current EL), IL = 32 bits [ 330.100791] SET = 0, FnV = 0 [ 330.103876] EA = 0, S1PTW = 0 [ 330.107078] Data abort info: [ 330.109978] ISV = 0, ISS = 0x00000005 [ 330.113896] CM = 0, WnR = 0 [ 330.117055] user pgtable: 4k pages, 39-bit VAs, pgd = ffffffc3a2ea6000 [ 330.123353] [0000000000000020] *pgd=0000000000000000, *pud=0000000000000000 [ 330.130924] Internal error: Oops: 96000005 [#1] PREEMPT SMP [ 330.136699] Modules linked in: [ 330.139630] CPU: 3 PID: 10671 Comm: user_process_camera_ Not tainted 4.9.108+ #124 [ 330.146930] Hardware name: jetson-xavier (DT) [ 330.151394] task: ffffffc36b921c00 task.stack: ffffffc3ed81c000 [ 330.157458] PC is at iommu_dma_alloc_iova+0xdc/0x130 [ 330.162502] LR is at iommu_dma_alloc_iova+0xdc/0x130 [ 330.167491] pc : [ ] lr : [ ] pstate: 80400145 [ 330.174925] sp : ffffffc3ed81f870 [ 330.178337] x29: ffffffc3ed81f880 x28: 0000000000000000 [ 330.183849] x27: 000000000000003f x26: ffffffc3ec0a4fb8 [ 330.189376] x25: 0000000000000000 x24: 0000000000000000 [ 330.194977] x23: 0000000000000001 x22: 000000ffffffffff [ 330.200910] x21: ffffffc3ec347800 x20: 0000000000002dfb [ 330.206086] x19: 000000000000000c x18: 0000000000000010 [ 330.211863] x17: 0000007fb7d40b10 x16: ffffff80082622c0 [ 330.217376] x15: 0000000000000006 x14: 64656e67696c615f [ 330.223313] x13: 657a69732c32313d x12: 7466696873206666 [ 330.229088] x11: 6666666666666666 x10: 203d74696d696c5f [ 330.234613] x9 : 00000000000007b8 x8 : 00000000000000c8 [ 330.240677] x7 : ffffff8009ed4f88 x6 : ffffffc3ffdf6c30 [ 330.246155] x5 : ffffffc370f65940 x4 : ffffffc3ffe03c80 [ 330.251236] x3 : 0000000000008183 x2 : ffffffc370f65900 [ 330.256825] x1 : 0000000000000009 x0 : 0000000000000000 [ 330.261910] [ 330.263340] Process user_process_camera_ (pid: 10671, stack limit = 0xffffffc3ed81c028) [ 330.270481] Call trace: [ 330.272861] [ ] iommu_dma_alloc_iova+0xdc/0x130 [ 330.278706] [ ] iommu_dma_alloc+0x378/0x450 [ 330.284053] [ ] __iommu_alloc_attrs+0xac/0x3f8 [ 330.289685] [ ] vb2_dc_alloc+0x140/0x1a0 [ 330.294720] [ ] __vb2_queue_alloc+0x15c/0x430 [ 330.300316] [ ] vb2_core_reqbufs+0x148/0x348 [ 330.305397] [ ] vb2_ioctl_reqbufs+0x78/0xa8 [ 330.310994] [ ] v4l_reqbufs+0x50/0x60 [ 330.315546] [ ] __video_do_ioctl+0x24c/0x2b8 [ 330.321141] [ ] video_usercopy+0x2cc/0x688 [ 330.326391] [ ] video_ioctl2+0x3c/0x50 [ 330.331382] [ ] v4l2_ioctl+0xf8/0x128 [ 330.336722] [ ] do_vfs_ioctl+0xb0/0x8f8 [ 330.342227] [ ] SyS_ioctl+0x94/0xa8 [ 330.347228] [ ] el0_svc_naked+0x34/0x38 [ 330.352393] ---[ end trace 733c07b2a206b1e2 ]--- How can we increase the DMA memory size to allocate more buffers ? Thanks in advance,

Hi, Please try r32.1. r31.1 is developer preview and we have enhancement in r32.1.

Hi, Thank you for your answer. I am running raw camera capture with the V4L2 driver API. I am not using the multimedia api. I am trying to allocate 9 buffers of 50MB for 4 sensors through the V4L2 ioctl VIDIOC_REQBUFS in four different threads: fd = open("/dev/videoX", O_RDWR); if (fd == -1) { perror("Opening video device"); } struct v4l2_requestbuffers req = { 0 }; req.count = 9; req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; req.memory = V4L2_MEMORY_MMAP; if (-1 == ioctl(fd, VIDIOC_REQBUFS, &req)) { perror("Requesting Buffer"); } With X going from 0 to 3 in “/dev/videoX”. I am also trying to modify the file hardware\nvidia\soc\t19x\kernel-dts\tegra194-soc\tegra194-soc-base.dtsi and more specifically the following node: common_as: common { iova-start = ; iova-size = ; alignment = ; num-pf-page = ; gap-page = ; }; I tried to modify the parameter iova-size from 0x7FF00000 to 0xFFF00000. This allows me to increase the number of allocated buffer but I have runtime issues as follow: [ 1184.872342] mc-err: vpr base=0:0, size=0, ctrl=1, override:(a01a8340, fcee10c1, 1, 0) [ 1184.872545] mc-err: (255) csw_viw: MC request violates VPR requirements [ 1184.872666] mc-err: status = 0x0ff74072; addr = 0xffffffff00; hi_adr_reg=008 [ 1184.872835] mc-err: secure: yes, access-type: write [ 1184.872970] mc-err: vpr base=0:0, size=0, ctrl=1, override:(a01a8340, fcee10c1, 1, 0) [ 1184.873114] mc-err: (255) csw_viw: MC request violates VPR requirements [ 1184.873231] mc-err: status = 0x0ff74072; addr = 0xffffffff00; hi_adr_reg=008 [ 1184.873356] mc-err: secure: yes, access-type: write [ 1184.873485] mc-err: vpr base=0:0, size=0, ctrl=1, override:(a01a8340, fcee10c1, 1, 0) [ 1184.873615] mc-err: (255) csw_viw: MC request violates VPR requirements [ 1184.873730] mc-err: status = 0x0ff74072; addr = 0xffffffff00; hi_adr_reg=008 [ 1184.874122] mc-err: secure: yes, access-type: write [ 1184.874551] mc-err: vpr base=0:0, size=0, ctrl=1, override:(a01a8340, fcee10c1, 1, 0) [ 1184.875243] mc-err: (255) csw_viw: MC request violates VPR requirements [ 1184.876156] mc-err: status = 0x0ff74072; addr = 0xffffffff00; hi_adr_reg=008 [ 1184.883787] mc-err: secure: yes, access-type: write [ 1184.888767] mc-err: Too many MC errors; throttling prints [ 1184.894412] __arm_smmu_context_fault: 141 callbacks suppressed [ 1184.894436] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x7c000000, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 [ 1185.068142] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x7c100800, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 [ 1185.071103] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x7804cc00, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 [ 1185.072287] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x74000000, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 [ 1185.072650] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x740174c0, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 [ 1185.073026] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x7402dbc0, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 [ 1185.073458] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x74045500, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 [ 1185.073808] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x7405cec0, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 [ 1185.074156] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x74071ac0, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 [ 1185.268050] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x740f8000, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 Do you have any idea what else should I do to increase the iova-size properly ? Thanks in advance,

Hi, We are checking if the setting can be customized. Will update.

Hi, common_as is general setting to multiple functions. Please try to ddd pixel_as specific to isp and vi functions. isp_domain { address-space = pixel_as >; sid-list = ; }; (...) vi_domain { address-space = pixel_as >; sid-list = ; }; (...) pixel_as: pixel { iova-start = ; iova-size = ; alignment = ; num-pf-page = ; gap-page = ; };

Hi, Thanks for your answer. I tried your patch and I can increase the number of buffers but I still have some errors: [ 523.541184] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x64000000, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 [ 523.541705] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x6401e800, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 [ 523.542055] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x64033f80, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 [ 523.542475] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x64049e40, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 [ 523.542823] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x64061f40, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 [ 523.543159] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x64076cc0, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 [ 523.544075] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x640a9740, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 [ 523.552381] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x642a00c0, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 [ 523.566177] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x645ddec0, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 [ 523.579841] t19x-arm-smmu 12000000.iommu: Unhandled context fault: smmu2, iova=0x6490e3c0, fsynr=0x11, cb=22, sid=4(0x4 - VI), pgd=0, pud=0, pmd=0, pte=0 I got only one mc-err which is far less than before and maybe not related: [ 361.921128] mc-err: vpr base=0:0, size=0, ctrl=1, override:(a01a8340, fcee10c1, 1, 0) [ 361.921139] mc-err: (255) csw_viw: MC request violates VPR requirements [ 361.921148] mc-err: status = 0x0ff74072; addr = 0xffffffff00; hi_adr_reg=008 [ 361.921153] mc-err: secure: yes, access-type: write The images I get from the V4L2 API are all empty. Do I have to specify elsewhere the memory increase allocated to the IOVA ? It looks like the memory management unit is not fully aware of the IOVA increased size ? Thanks in advance,

Hi, If your sensors are hard linked to Xavier CSI ports, you may check [Sensor Driver Programming Guide] to modify device tree accordingly.

Hi, The [Sensor Driver Programming Guide] does not talk about memory allocation. It seems that the issue is more a Linux kernel issue than a sensor issue. I would like to increase the DMA zone area and with your patch I managed to do that but the rest of the kernel seems to be unaware of this modification hence the unhandled context fault. How could I increase the DMA zone area on the Jetson Xavier ? Thanks in advance,

Hi, Is your sensor USB camera, YUV sensor via Xavier CSI port, or Bayer sensor via Xavier CSI port?

Hi, The sensor is a 10-bit RAW sensor connected via Xavier CSI port. It’s the OV24A1B sensor from omnivision. Kind regards,

[V4L2] VIDIOC_REQBUFS cannot allocate more than 2GB of buffer

Robotics & Edge Computing Jetson Systems Jetson AGX Xavier

DaneLLL March 14, 2019, 2:43am 2

Hi,
It is not clear if you run camera capture, video encoding, video decoding. We have samples at tegra_multimedia_api\samples. Please check these samples and make a patch on either one so that we can try to reproduce it.

We have max buffer number definition in all cases. 32 is a very large number and should exceed limitation of all cases.

Can’t request more than 32 buffers with v4l2 V4L2_MEMORY_USERPTR/MMAP

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[V4L2] VIDIOC_REQBUFS cannot allocate more than 2GB of buffer

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