From: Qian Cai <cai@lca.pw>
To: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Cc: f.fainelli@gmail.com, mbrugger@suse.com, marc.zyngier@arm.com,
catalin.marinas@arm.com, Robin Murphy <robin.murphy@arm.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Rob Herring <robh+dt@kernel.org>,
wahrenst@gmx.net, m.szyprowski@samsung.com,
phill@raspberrypi.org, will@kernel.org,
Christoph Hellwig <hch@lst.de>,
linux-arm-kernel@lists.infradead.org,
linux-rpi-kernel@lists.infradead.org
Subject: Re: [PATCH v6 3/4] arm64: use both ZONE_DMA and ZONE_DMA32
Date: Mon, 21 Oct 2019 10:46:23 -0400 [thread overview]
Message-ID: <5E3CD9CA-76C3-4D46-BA0B-DEBF650E8950@lca.pw> (raw)
In-Reply-To: <78caa5bcfc0d59e8ec5d6b7060df76896d25248b.camel@suse.de>
> On Oct 21, 2019, at 10:34 AM, Nicolas Saenz Julienne <nsaenzjulienne@suse.de> wrote:
>
> On Mon, 2019-10-21 at 10:15 -0400, Qian Cai wrote:
>>> On Sep 11, 2019, at 2:25 PM, Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
>>> 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@suse.de>
>>> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
>>>
>>> ---
>>
>> With ZONE_DMA=y, this config will fail to reserve 512M CMA on a server,
>>
>> https://raw.githubusercontent.com/cailca/linux-mm/master/arm64.config
>>
>> CONFIG_DMA_CMA=y
>> CONFIG_CMA_SIZE_MBYTES=64
>> CONFIG_CMA_SIZE_SEL_MBYTES=y
>> CONFIG_CMA_ALIGNMENT=8
>> CONFIG_CMA=y
>> CONFIG_CMA_DEBUGFS=y
>> CONFIG_CMA_AREAS=7
>>
>> Is this expected?
>
> Not really, just tested cma=512M on a Raspberry Pi4, and it went well. The only
> thing on my build that differs from your config is CONFIG_CMA_DEBUGFS.
>
> Could you post more information on the device you're experiencing this on? Also
> some logs.
With the above config, it does not even need "cma=512M" kernel cmdline.
[ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x431f0af1]
[ 0.000000] Linux version 5.4.0-rc4-next-20191021+ (clang version 8.0.1 (Red Hat 8.0.1-1.module+el8.1.0+3866+6be7f4d8)) #1 SMP Mon Oct 21 10:03:03 EDT 2019
[ 0.000000] Setting debug_guardpage_minorder to 1
[ 0.000000] efi: Getting EFI parameters from FDT:
[ 0.000000] efi: EFI v2.70 by American Megatrends
[ 0.000000] efi: ESRT=0xf935ed98 SMBIOS=0xfcc90000 SMBIOS 3.0=0xfcc80000 ACPI 2.0=0xfac80000 MEMRESERVE=0xfacd1018
[ 0.000000] esrt: Reserving ESRT space from 0x00000000f935ed98 to 0x00000000f935edd0.
[ 0.000000] crashkernel reserved: 0x00000097db400000 - 0x00000097fb400000 (512 MB)
[ 0.000000] cma: Reserved 512 MiB at 0x00000000a0000000
With ZONE_DMA=y, it will say,
cma: Failed to reserve 512 MiB
The machine is a ThunderX2 server.
https://buy.hpe.com/us/en/servers/apollo-systems/apollo-70-system/apollo-70-system/hpe-apollo-70-system/p/1010742472
# lscpu
Architecture: aarch64
Byte Order: Little Endian
CPU(s): 256
On-line CPU(s) list: 0-255
Thread(s) per core: 4
Core(s) per socket: 32
Socket(s): 2
NUMA node(s): 2
Vendor ID: Cavium
Model: 1
Model name: ThunderX2 99xx
Stepping: 0x1
BogoMIPS: 400.00
L1d cache: 32K
L1i cache: 32K
L2 cache: 256K
L3 cache: 32768K
NUMA node0 CPU(s): 0-127
NUMA node1 CPU(s): 128-255
Flags: fp asimd aes pmull sha1 sha2 crc32 atomics cpuid asimdrdm
next prev parent reply other threads:[~2019-10-21 14:46 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-11 18:25 [PATCH v6 0/4] Raspberry Pi 4 DMA addressing support Nicolas Saenz Julienne
2019-09-11 18:25 ` [PATCH v6 1/4] arm64: mm: use arm64_dma_phys_limit instead of calling max_zone_dma_phys() Nicolas Saenz Julienne
2019-09-11 18:25 ` [PATCH v6 2/4] arm64: rename variables used to calculate ZONE_DMA32's size Nicolas Saenz Julienne
2019-09-11 18:25 ` [PATCH v6 3/4] arm64: use both ZONE_DMA and ZONE_DMA32 Nicolas Saenz Julienne
2019-10-21 14:15 ` Qian Cai
2019-10-21 14:34 ` Nicolas Saenz Julienne
2019-10-21 14:46 ` Qian Cai [this message]
2019-10-21 17:01 ` Nicolas Saenz Julienne
2019-10-21 17:25 ` Qian Cai
2019-10-21 17:55 ` Nicolas Saenz Julienne
2019-10-21 20:36 ` Qian Cai
2019-10-22 11:23 ` Nicolas Saenz Julienne
2019-10-23 7:11 ` Matthias Brugger
2019-10-31 15:51 ` Catalin Marinas
2019-10-31 16:04 ` Nicolas Saenz Julienne
2019-10-31 18:02 ` Catalin Marinas
2019-10-31 18:11 ` Nicolas Saenz Julienne
2019-10-31 18:13 ` Catalin Marinas
2019-12-03 5:08 ` John Stultz
2019-12-03 5:38 ` John Stultz
2019-12-03 6:03 ` John Stultz
2019-12-03 10:12 ` Will Deacon
2019-12-03 11:19 ` Catalin Marinas
2019-09-11 18:25 ` [PATCH v6 4/4] mm: refresh ZONE_DMA and ZONE_DMA32 comments in 'enum zone_type' Nicolas Saenz Julienne
2019-10-01 16:05 ` [PATCH v6 0/4] Raspberry Pi 4 DMA addressing support Catalin Marinas
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