Re: [PATCH net-next 3/4] selftests/net: ncdevmem: add -b option to set rx-buf-size on bind

[Stanislav Fomichev]

On 06/03, Bobby Eshleman wrote:
> From: Bobby Eshleman <bobbyeshleman@xxxxxxxx>
> 
> Add -b <bytes> to request a non-default niov size via
> NETDEV_A_DMABUF_RX_BUF_SIZE. When the value exceeds PAGE_SIZE,
> udmabuf_alloc() switches to an MFD_HUGETLB-backed memfd so each 2 MB
> hugepage produces one naturally-aligned sg entry.
> 
> Reject values > 2 MB up front: MFD_HUGETLB + udmabuf can only guarantee
> 2 MB per sg entry (one hugepage), so a larger rx_buf_size would fail the
> per-sg length/alignment check.
> 
> Add CONFIG_HUGETLBFS=y to drivers/net/hw/config so the new path is
> reachable in the CI kernels built for these tests.

I vaguely remember there was also some kernel cmdline argument to
reserve these? Do we need to also do something to NIPA to reserve 2MB
pages for this test? Or was it for 1GB pages?