On Thu, Nov 23, 2023 at 4:52 PM <christian.ehrha...@canonical.com> wrote:
> From: David Wilder <dwil...@us.ibm.com>
>
> When using --no-huge option physical address are not guaranteed
> to be persistent.
>
> This change effectively makes "--no-huge" the same as
> "--no-huge --iova-mode=va".
>
> When --no-huge is used (or any other condition making physical
> addresses unavailable) setting --iova-mode=pa will have no effect.
>
> Signed-off-by: Christian Ehrhardt <christian.ehrha...@canonical.com>
> ---
> doc/guides/prog_guide/env_abstraction_layer.rst | 9 ++++++---
> lib/eal/linux/eal.c | 14 ++++++++------
> 2 files changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/doc/guides/prog_guide/env_abstraction_layer.rst
> b/doc/guides/prog_guide/env_abstraction_layer.rst
> index 6debf54efb..20c7355e0f 100644
> --- a/doc/guides/prog_guide/env_abstraction_layer.rst
> +++ b/doc/guides/prog_guide/env_abstraction_layer.rst
> @@ -559,9 +559,12 @@ IOVA Mode is selected by considering what the current
> usable Devices on the
> system require and/or support.
>
> On FreeBSD, RTE_IOVA_PA is always the default. On Linux, the IOVA mode is
> -detected based on a 2-step heuristic detailed below.
> +detected based on a heuristic detailed below.
>
> -For the first step, EAL asks each bus its requirement in terms of IOVA
> mode
> +For the first step, if no Physical Addresses are available RTE_IOVA_VA is
> +selected.
> +
> +Then EAL asks each bus its requirement in terms of IOVA mode
> and decides on a preferred IOVA mode.
>
> - if all buses report RTE_IOVA_PA, then the preferred IOVA mode is
> RTE_IOVA_PA,
> @@ -575,7 +578,7 @@ and decides on a preferred IOVA mode.
> If the buses have expressed no preference on which IOVA mode to pick,
> then a
> default is selected using the following logic:
>
> -- if physical addresses are not available, RTE_IOVA_VA mode is used
> +- if enable_iova_as_pa was not set at build RTE_IOVA_VA mode is used
> - if /sys/kernel/iommu_groups is not empty, RTE_IOVA_VA mode is used
> - otherwise, RTE_IOVA_PA mode is used
>
> diff --git a/lib/eal/linux/eal.c b/lib/eal/linux/eal.c
> index 57da058cec..7d0eedef57 100644
> --- a/lib/eal/linux/eal.c
> +++ b/lib/eal/linux/eal.c
> @@ -1067,6 +1067,14 @@ rte_eal_init(int argc, char **argv)
>
> phys_addrs = rte_eal_using_phys_addrs() != 0;
>
> + if (!phys_addrs) {
> + /* if we have no access to physical addresses,
> + * pick IOVA as VA mode.
> + */
> + iova_mode = RTE_IOVA_VA;
>
^^ this won't work, thanks for trying to rush it :-/
I'll fix and test it before v2
But since it wasn't my patch initially I'm happy if anyone else wants to
take over ...
> + RTE_LOG(INFO, EAL, "Physical addresses are unavailable,
> selecting IOVA as VA mode.\n");
> + }
> +
> /* if no EAL option "--iova-mode=<pa|va>", use bus IOVA scheme */
> if (internal_conf->iova_mode == RTE_IOVA_DC) {
> /* autodetect the IOVA mapping mode */
> @@ -1078,12 +1086,6 @@ rte_eal_init(int argc, char **argv)
> if (!RTE_IOVA_IN_MBUF) {
> iova_mode = RTE_IOVA_VA;
> RTE_LOG(DEBUG, EAL, "IOVA as VA mode is
> forced by build option.\n");
> - } else if (!phys_addrs) {
> - /* if we have no access to physical
> addresses,
> - * pick IOVA as VA mode.
> - */
> - iova_mode = RTE_IOVA_VA;
> - RTE_LOG(DEBUG, EAL, "Physical addresses
> are unavailable, selecting IOVA as VA mode.\n");
> } else if (is_iommu_enabled()) {
> /* we have an IOMMU, pick IOVA as VA mode
> */
> iova_mode = RTE_IOVA_VA;
> --
> 2.34.1
>
>
--
Christian Ehrhardt
Director of Engineering, Ubuntu Server
Canonical Ltd
