ghall
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RPi 3 with BCM2835 ???

Mon Jul 17, 2017 7:48 pm

Hello,

I have an RPi 3 board (marked RPi 3 v1.2 on the board) that I purchased about 1/2 year ago. Within Raspbian, cat /proc/cpuinfo indicates the following:
Hardware : BCM2835
Revision : a22082
Processors are ARMv7 rev 4.

I thought that the RPi3's have BCM2837's? Does this seem correct to you?

Thanks....gary

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Re: RPi 3 with BCM2835 ???

Tue Jul 18, 2017 1:13 am

Pi3B and Pi2Bv1.2 both use the BCM2837. The BCM2835 has a single ARMv6. The Pi2Bv1.1 used a BCM2836, which had ARMv7 CPUs. What's more, all Pis made with BCM2835 SoCs use PoP RAM, so--unless you start taking it apart--you can't even *see* the BCM2835 markings.

Net result... Are you sure you are looking at a Pi3B and not a Pi2Bv1.1? Are you sure the SoC is labeled BCM2835 and not BCM2836? What is silk screened on the PCB just below the GPIO pins (the model and version is printed there)?

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Re: RPi 3 with BCM2835 ???

Tue Jul 18, 2017 2:09 am

W. H. Heydt wrote:Pi3B and Pi2Bv1.2 both use the BCM2837. The BCM2835 has a single ARMv6. The Pi2Bv1.1 used a BCM2836, which had ARMv7 CPUs. What's more, all Pis made with BCM2835 SoCs use PoP RAM, so--unless you start taking it apart--you can't even *see* the BCM2835 markings.

Net result... Are you sure you are looking at a Pi3B and not a Pi2Bv1.1? Are you sure the SoC is labeled BCM2835 and not BCM2836? What is silk screened on the PCB just below the GPIO pins (the model and version is printed there)?
Note the OP already gave the silkscreen version number and did not mention reading the part number from the chip.

On my RPi 3B, cat /proc/cpuinfo, returns the same information as shown by the OP.
Hardware : BCM2835
model name : ARMv7 Processor rev 4 (v7l)


My RPi 2B V1.1 gives this:
Hardware : BCM2835
model name : ARMv7 Processor rev 5 (v7l)

Note that the 2B v1.1 is rev 5 and the 3B is rev 4 which seems odd.
Unless specified otherwise my response is based on the latest and fully updated Raspbian Buster w/ Desktop OS.

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Re: RPi 3 with BCM2835 ???

Tue Jul 18, 2017 8:44 am

Looks like cpuinfo doesn't have the correct value. Not sure why, I'll ask Dom/ANother if it can be sorted.

Note, on a Pi3 board a BCM2835 would not fit or work....
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ghall
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Re: RPi 3 with BCM2835 ???

Wed Jul 19, 2017 12:49 am

Interesting, the chip is stamped as BCM2837RIFBG. So I guess cpuinfo is wrong.

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Re: RPi 3 with BCM2835 ???

Wed Jul 19, 2017 7:31 am

Pretty sure the wrong identification is because Raspbian is not optimized for the 64-bit ARM Cortex A53 (ARMv8) SoC used on the Pi3.
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Re: RPi 3 with BCM2835 ???

Wed Jul 19, 2017 9:09 am

It's just a kernel/device tree anomaly.
Upstream have chosen to denote all the Pi's as BCM2835, whereas the original Pi specific kernels would display BCM2708, BCM2709, or BCM2710 as appropriate.

Whether it is more correct to use 2708/9/10 or 2835/6/7 is also sometimes debated - the former are the silicon, the latter are the packaged chip (which in some non-Pi cases also included an independent RAM die within the same package).
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ghall
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Re: RPi 3 with BCM2835 ???

Wed Jul 19, 2017 1:26 pm

Thank you everyone for your replies !
....gary

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Re: RPi 3 with BCM2835 ???

Wed Jul 19, 2017 2:50 pm

Revision : a22082

Means it's a PRC (China) made Pi3, just like one of mine.

ghall
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Re: RPi 3 with BCM2835 ???

Mon Jul 24, 2017 1:20 pm

I'm going to buy a "Made in UK" board to compare. I don't know if true or not, but I've heard they are better built.

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Re: RPi 3 with BCM2835 ???

Mon Jul 24, 2017 1:28 pm

ghall wrote:I'm going to buy a "Made in UK" board to compare. I don't know if true or not, but I've heard they are better built.
all FUD
they are the same as the Japanese ones .... FYI
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Re: RPi 3 with BCM2835 ???

Mon Jul 24, 2017 1:47 pm

ghall wrote:I'm going to buy a "Made in UK" board to compare. I don't know if true or not, but I've heard they are better built.
There is no difference. They all pass the same tests after manufacture.
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Re: RPi 3 with BCM2835 ???

Mon Jul 24, 2017 2:22 pm

ghall wrote:I'm going to buy a "Made in UK" board to compare. I don't know if true or not, but I've heard they are better built.
I have both, go ahead and do it.
Because then you'll have another Pi3 :-D
though I wouldn't pay extra specifically for a UK version.

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Re: RPi 3 with BCM2835 ???

Tue Nov 07, 2017 9:54 am

This, as 6by9 indicated, is due to the fact that the upstream ARM kernel only allows us to set a single value for our devices. If we wanted to have multiple different values it would require that we edit the code (which in general we prefer not to do because it causes problems for us when integrating changes from upstream).

I've asked Phil to change this to instead return "BCM28xx" to indicate that the kernel is specifically for the BCM2805/6/7 silicon.

If you'd like to find out the model of the computer you should use the device tree instead a la:

Code: Select all

[email protected]:~ $ cat /proc/device-tree/model
Raspberry Pi 3 Model B Rev 1.2
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