On Wed, Sep 11, 2019 at 11:26 AM Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx> wrote: > So far all arm64 devices have supported 32 bit DMA masks for their > peripherals. This is not true anymore for the Raspberry Pi 4 as most of > it's peripherals can only address the first GB of memory on a total of > up to 4 GB. > > This goes against ZONE_DMA32's intent, as it's expected for ZONE_DMA32 > to be addressable with a 32 bit mask. So it was decided to re-introduce > ZONE_DMA in arm64. > > ZONE_DMA will contain the lower 1G of memory, which is currently the > memory area addressable by any peripheral on an arm64 device. > ZONE_DMA32 will contain the rest of the 32 bit addressable memory. > > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx> > Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx> Hey Nicolas, Testing the db845c with linus/master, I found a regression causing system hangs in early boot: [ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x517f803c] [ 0.000000] Linux version 5.4.0-mainline-10675-g957a03b9e38f (docker@a4ec90a1e72c) (gcc version 7.4.0 (Ubuntu/Linaro 7.4.0-1ubuntu1~18.04.1)) #1209 SMP PREEMPT Tue Dec 3 00:23:15 UTC 2019 [ 0.000000] Machine model: Thundercomm Dragonboard 845c [ 0.000000] earlycon: qcom_geni0 at MMIO 0x0000000000a84000 (options '115200n8') [ 0.000000] printk: bootconsole [qcom_geni0] enabled [ 0.000000] efi: Getting EFI parameters from FDT: [ 0.000000] efi: UEFI not found. [ 0.000000] cma: Reserved 16 MiB at 0x00000000ff000000 [ 0.000000] psci: probing for conduit method from DT. [ 0.000000] psci: PSCIv1.1 detected in firmware. [ 0.000000] psci: Using standard PSCI v0.2 function IDs [ 0.000000] psci: MIGRATE_INFO_TYPE not supported. [ 0.000000] psci: SMC Calling Convention v1.0 [ 0.000000] psci: OSI mode supported. [ 0.000000] percpu: Embedded 31 pages/cpu s87512 r8192 d31272 u126976 [ 0.000000] Detected VIPT I-cache on CPU0 [ 0.000000] CPU features: detected: GIC system register CPU interface [ 0.000000] CPU features: kernel page table isolation forced ON by KASLR [ 0.000000] CPU features: detected: Kernel page table isolation (KPTI) [ 0.000000] ARM_SMCCC_ARCH_WORKAROUND_1 missing from firmware [ 0.000000] CPU features: detected: Hardware dirty bit management [ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: -188245 [ 0.000000] Kernel command line: earlycon firmware_class.path=/vendor/firmware/ androidboot.hardware=db845c init=/init androidboot.boot_devices=soc/1d84000.ufshc printk.devkmsg=on buildvariant=userdebug root=/dev/sda2 androidboot.bootdevice=1d84000.ufshc androidboot.serialno=c4e1189c androidboot.baseband=sda msm_drm.dsi_display0=dsi_lt9611_1080_video_display: androidboot.slot_suffix=_a skip_initramfs rootwait ro init=/init <hangs indefinitely here> I bisected the issue down to this patch (1a8e1cef7603 upstream - the previous patch a573cdd7973d works though I need to apply the arm64_dma_phys_limit bit from this one as the previous patch doesn't build on its own). In the above log: [ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: -188245 looks the most suspect, and going back to the working a573cdd7973d + build fix I see: [ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 957419 Do you have any suggestions for what might be going wrong? thanks -john
