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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [ImageBuilder] uboot-script-gen: Add ability to configure static event channels
On Mon, 29 Sep 2025, Oleksandr Tyshchenko wrote:
> Add DOMU_STATIC_EVTCHNS[number]="local_id local_port remote_id; ..."
> configuration file string option specifying the static event channel
> definitions for domain.
>
> The build script uses simple IDs to automatically and safely
> generate the required unique phandle numbers for the device tree.
> The user only needs to define simple numeric IDs and does not need
> to manage complex phandle values.
>
> For the following example:
> DOMU_STATIC_EVTCHNS[0]="1 10 2; 3 12 4"
> DOMU_STATIC_EVTCHNS[1]="2 11 1; 4 13 3"
>
> it generates:
> fdt mknod /chosen/domU0 evtchn@1
> fdt set /chosen/domU0/evtchn@1 phandle <0xfffffffe>
> fdt set /chosen/domU0/evtchn@1 compatible "xen,evtchn-v1"
> fdt set /chosen/domU0/evtchn@1 xen,evtchn <10 0xfffffffd>
> fdt mknod /chosen/domU0 evtchn@3
> fdt set /chosen/domU0/evtchn@3 phandle <0xfffffffc>
> fdt set /chosen/domU0/evtchn@3 compatible "xen,evtchn-v1"
> fdt set /chosen/domU0/evtchn@3 xen,evtchn <12 0xfffffffb>
> ...
> fdt mknod /chosen/domU1 evtchn@2
> fdt set /chosen/domU1/evtchn@2 phandle <0xfffffffd>
> fdt set /chosen/domU1/evtchn@2 compatible "xen,evtchn-v1"
> fdt set /chosen/domU1/evtchn@2 xen,evtchn <11 0xfffffffe>
> fdt mknod /chosen/domU1 evtchn@4
> fdt set /chosen/domU1/evtchn@4 phandle <0xfffffffb>
> fdt set /chosen/domU1/evtchn@4 compatible "xen,evtchn-v1"
> fdt set /chosen/domU1/evtchn@4 xen,evtchn <13 0xfffffffc>
I'd like to make an alternative suggestion. The user specifies triplets:
DOMU_STATIC_EVTCHNS[0]="local-id remote-domid remote-id
To generate the example above:
DOMU_STATIC_EVTCHNS[0]="10 1 11; 12 1 13"
DOMU_STATIC_EVTCHNS[1]="11 0 10; 13 0 12"
I think this is better because it doesn't require to invent (useless)
unique numbers as references. Instead, it focuses on the data that
actually matters to the user: the event channel IDs at both ends and
the domains involved. These are things the user must know anyway.
The only catch with this suggesion is the definition of "remote-domid":
in reality the DOMU array index is not the domid in dom0less so we would
have to clarify. Maybe we could define it as remote-domain-index or
something like that.
What do you think?
In ImageBuilder so far we have not used separators like ';' here but I
think it does improve readability so I would keep it.
> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> ---
> README.md | 21 ++++++++++
> scripts/uboot-script-gen | 7 ++++
> scripts/xen_dt_domu | 89 ++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 117 insertions(+)
>
> diff --git a/README.md b/README.md
> index 7b68cf5..52ed1f7 100644
> --- a/README.md
> +++ b/README.md
> @@ -218,6 +218,27 @@ Where:
> DOMU_VCPU_HARD_AFFINITY[number,1]="3"
> ```
>
> +- DOMU_STATIC_EVTCHNS[number]="local_id local_port remote_id; ..."
> + if specified, this parameter allows the configuration of static event
> channels
> + for inter-domain communication. Each entry in DOMU_STATIC_EVTCHNS[number]
> + specifies one or more event channels for a particular domain.
> + The configuration format for each event channel definition is a set of
> + three values:
> + - local_id: A simple, unique integer that identifies the local endpoint
> of
> + the event channel. This ID must be unique across all domains.
> + - local_port: The numeric port number for the local endpoint.
> + - remote_id: The ID of the corresponding remote endpoint to which this
> + the local port connects.
> +
> + Multiple event channel definitions for a single domain can be provided by
> + separating them with a semicolon (;).
> +
> + Below is an example that creates two pairs of bidirectional channels
> between
> + two domains:
> + NUM_DOMUS=2
> + DOMU_STATIC_EVTCHNS[0]="1 10 2; 3 12 4"
> + DOMU_STATIC_EVTCHNS[1]="2 11 1; 4 13 3"
> +
> - DOMU_COLORS[number] specifies the colors (cache coloring) to be used
> for the domain and is in the format startcolor-endcolor
>
> diff --git a/scripts/uboot-script-gen b/scripts/uboot-script-gen
> index 4f92610..003a622 100755
> --- a/scripts/uboot-script-gen
> +++ b/scripts/uboot-script-gen
> @@ -428,6 +428,8 @@ function xen_device_tree_editing()
> fi
> fi
>
> + xen_dt_build_evtchns_map
> +
> i=0
> while test $i -lt $NUM_DOMUS
> do
> @@ -512,6 +514,11 @@ function xen_device_tree_editing()
>
> xen_dt_domu_add_vcpu_nodes "/chosen/domU$i" $i ${DOMU_VCPUS[$i]}
>
> + if test "${DOMU_STATIC_EVTCHNS[$i]}"
> + then
> + xen_dt_domu_add_evtchns "/chosen/domU$i"
> "${DOMU_STATIC_EVTCHNS[$i]}"
> + fi
> +
> add_device_tree_kernel "/chosen/domU$i" "domU${i}_kernel"
> ${domU_kernel_addr[$i]} ${domU_kernel_size[$i]} "${DOMU_CMD[$i]}"
> if test "${domU_ramdisk_addr[$i]}"
> then
> diff --git a/scripts/xen_dt_domu b/scripts/xen_dt_domu
> index 8134896..97c5325 100644
> --- a/scripts/xen_dt_domu
> +++ b/scripts/xen_dt_domu
> @@ -37,3 +37,92 @@ function xen_dt_domu_add_vcpu_nodes()
> fi
> done
> }
> +
> +declare -A EVTCHN_ID_TO_PHANDLE_MAP
> +
> +function xen_dt_build_evtchns_map()
> +{
> + local i
> + local evtchn_str # The full event channel definition string
> + local def
> + local local_id remote_id id
> + local new_phandle
> +
> + for (( i=0; i<$NUM_DOMUS; i++ ))
> + do
> + evtchn_str=${DOMU_STATIC_EVTCHNS[$i]}
> + if test -z "$evtchn_str"
> + then
> + continue
> + fi
> +
> + IFS=';' read -ra evtchn_defs <<< "$evtchn_str"
> +
> + # Loop over each definition and process both local and remote IDs
> + for def in "${evtchn_defs[@]}"
> + do
> + read -r local_id _ remote_id <<< "$def"
> + if test -z "$local_id" || test -z "$remote_id"
> + then
> + echo "Malformed evtchn definition: '$def'"
> + cleanup_and_return_err
> + fi
> +
> + if [[ "$local_id" == "$remote_id" ]]
> + then
> + echo "Invalid evtchn definition: '$def'"
> + cleanup_and_return_err
> + fi
> +
> + for id in $local_id $remote_id
> + do
> + # If this ID is not already in our map, assign it a new
> phandle
> + if [[ ! -v EVTCHN_ID_TO_PHANDLE_MAP[$id] ]]
> + then
> + get_next_phandle new_phandle
> + EVTCHN_ID_TO_PHANDLE_MAP[$id]=$new_phandle
> + echo "evtchn ID '$id' is assigned phandle '$new_phandle'"
> + fi
> + done
> + done
> + done
> +}
> +
> +function xen_dt_domu_add_evtchns()
> +{
> + # $1 - dt path
> + local path=$1
> + # $2 - The full event channel definition string
> + local evtchn_str=$2
> +
> + local def
> + local local_id local_port remote_id
> + local local_phandle remote_phandle
> +
> + IFS=';' read -ra evtchn_defs <<< "$evtchn_str"
> +
> + # Loop over each definition and create a node for it
> + for def in "${evtchn_defs[@]}"
> + do
> + read -r local_id local_port remote_id <<< "$def"
> + if test -z "$local_id" || test -z "$local_port" || test -z
> "$remote_id"
> + then
> + echo "Malformed evtchn definition: '$def'"
> + cleanup_and_return_err
> + fi
> +
> + # Look up the phandles from our globally-populated map
> + local_phandle=${EVTCHN_ID_TO_PHANDLE_MAP[$local_id]}
> + remote_phandle=${EVTCHN_ID_TO_PHANDLE_MAP[$remote_id]}
> + if test -z "$local_phandle" || test -z "$remote_phandle"
> + then
> + echo "Could not find phandle for evtchn ID '$local_id' or
> '$remote_id'"
> + cleanup_and_return_err
> + fi
> +
> + dt_mknode "${path}" "evtchn@$local_id"
> + dt_set "${path}/evtchn@$local_id" "phandle" "hex" "$local_phandle"
> + dt_set "${path}/evtchn@$local_id" "compatible" "str" "xen,evtchn-v1"
> + dt_set "${path}/evtchn@$local_id" "xen,evtchn" "hex" "$local_port
> $remote_phandle"
> + done
> +}
> --
> 2.34.1
>
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