From: David Hildenbrand on
gitlab.com
https://gitlab.com/cki-project/kernel-ark/-/merge_requests/1171#note_6161...
With kata-containers we run VMs as small as 256 MiB (or sometimes even
smaller). However, in these setups, we run a stripped-down OS, so we can
expect to kdump never to be installed/active (and IIUC, that implies that we
never do a crashkernel reservation). At least that's what I assume.
Note that [RHEL documents "Recommended minimum RAM"
](https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/htm
l/performing_a_standard_rhel_installation/system-requirements-
reference_installing-rhel), with a note that "It is possible to complete the
installation with less memory than the recommended minimum requirements. The
exact requirements depend on your environment and installation path.". So it
might work with more or less. I wouldn't be surprised if people are running
1GiB VMs with RHEL8; the question is, if these setups default-install kdump (I
assume so?), and if we care for new versions of RHEL.
On small VMs, we end up "wasting" a significant amount of memory on kdump
reservations, which makes me believe that kdump isn't actually a good fit for
small VMs at all, especially with newer RHEL kernels. So if we assume that
people with less than 1.5G don't need kdump, why care at all about "we have
another RHEL only patch to round up the memblock collected system ram size by
128M"?
I don't immediately see why the switch from 1G-4G to 0G-4G is actually helpful
and I'd just leave it like that and have kdump disabled for machines that have
a memblock size < 1 GiB. Can you clarify what I am missing?