[dpdk-dev] FreeBSD 13 Memory / Contigmem Issues With Booting

[Bruce Richardson]

On Wed, Jun 16, 2021 at 04:24:05PM -0400, Brandon Lo wrote:
> Hi everyone,
> 
> I have been trying to expand the UNH IOL unit testing coverage over to
> FreeBSD 13.
> Following this documentation:
> https://doc.dpdk.org/guides/freebsd_gsg/build_dpdk.html#loading-the-dpdk-contigmem-module
> 
> I compiled the contigmem kernel module from the latest DPDK v21.05 and
> set the variables in /boot/loader.conf.
> This results in a kernel trap 12 on boot with a machine that has 4GB
> of RAM available and 1 GB assigned for contigmem.
> 
> If I only set the loader.conf to load the contigmem kernel module
> without setting any variables, then it boots fine.
> However, using these default settings, DPDK unit tests (fast-suite)
> fail in some of the test cases.
> 
> Is this a memory-related issue where the virtual machine does not have
> enough memory allocated (if so, how much RAM is needed?),
> or is it related to compatibility issues between the different FreeBSD versions?
>
Given that the defaults if you don't specify a loader.conf value is to use
is 512MB, I suspect that it is indeed the case, and that the kernel is
struggling to find a single block of 1GB for use.

In terms of how much memory is needed, I'm not sure, it may take a bit of
trial and error to determine. What tests are needing more than 512MB of
RAM? I would have thought that that should have been plenty for most cases.

Another option to try rather than allocating a single 1GB block is to
attempt to create e.g. 2x 512MB or 3x 256MB blocks and see if that works,
or helps with the unit tests.

Regards,
/Bruce