[PATCH v2] cmd: pxe: add alias devicetree-overlay for fdtoverlays
Neil Armstrong
neil.armstrong at linaro.org
Wed Sep 21 15:30:11 CEST 2022
On 21/09/2022 15:26, Edoardo Tomelleri wrote:
> This adds keyword devicetree-overlay as an alias for fdtoverlays in
> extlinux (sysboot) and pxe to better follow the Boot Loader Specification
> [1], improves documentation around them by adding an example for both
> fdtoverlays and devicetree-overlay and the environment variable required
> for this feature. The link for the spec is updated to the current one.
>
> [1] https://systemd.io/BOOT_LOADER_SPECIFICATION/
>
> Signed-off-by: Edoardo Tomelleri <e.tomell at gmail.com>
> ---
>
> Changes in v2:
> - Updated link to Boot Loader Specification
> - Added link to Boot Loader Specification to the patch commit
> - Changed README.pxe reusing the same wording as of the aliased commands
>
> boot/pxe_utils.c | 2 ++
> doc/README.pxe | 12 ++++++++++++
> doc/develop/distro.rst | 32 +++++++++++++++++++++++++++++---
> 3 files changed, 43 insertions(+), 3 deletions(-)
>
> diff --git a/boot/pxe_utils.c b/boot/pxe_utils.c
> index a364fa8bb5..d5c215ae2c 100644
> --- a/boot/pxe_utils.c
> +++ b/boot/pxe_utils.c
> @@ -380,6 +380,7 @@ err:
>
> /**
> * label_boot_fdtoverlay() - Loads fdt overlays specified in 'fdtoverlays'
> + * or 'devicetree-overlay'
> *
> * @ctx: PXE context
> * @label: Label to process
> @@ -809,6 +810,7 @@ static const struct token keywords[] = {
> {"devicetreedir", T_FDTDIR},
> {"fdtdir", T_FDTDIR},
> {"fdtoverlays", T_FDTOVERLAYS},
> + {"devicetree-overlay", T_FDTOVERLAYS},
> {"ontimeout", T_ONTIMEOUT,},
> {"ipappend", T_IPAPPEND,},
> {"background", T_BACKGROUND,},
> diff --git a/doc/README.pxe b/doc/README.pxe
> index 75caa01c4a..d14d2bdcc9 100644
> --- a/doc/README.pxe
> +++ b/doc/README.pxe
> @@ -163,6 +163,13 @@ fdtoverlays <path> [...] - if this label is chosen, use tftp to retrieve the DT
> and then applied in the load order to the fdt blob stored at the
> address indicated in the fdt_addr_r environment variable.
>
> +devicetree-overlay <path> [...] - if this label is chosen, use tftp to retrieve the DT
> + overlay(s) at <path>. it will be temporarily stored at the
> + address indicated in the fdtoverlay_addr_r environment variable,
> + and then applied in the load order to the fdt blob stored at the
> + address indicated in the fdt_addr_r environment variable.
> + Alias for fdtoverlays.
> +
> kaslrseed - set this label to request random number from hwrng as kaslr seed.
>
> append <string> - use <string> as the kernel command line when booting this
> @@ -178,6 +185,11 @@ fdt <path> - if this label is chosen, use tftp to retrieve the fdt blob
> the fdt_addr_r environment variable, and that address will
> be passed to bootm.
>
> +devicetree <path> - if this label is chosen, use tftp to retrieve the fdt blob
> + at <path>. it will be stored at the address indicated in
> + the fdt_addr_r environment variable, and that address will
> + be passed to bootm. Alias for fdt.
> +
> fdtdir <path> - if this label is chosen, use tftp to retrieve a fdt blob
> relative to <path>. If the fdtfile environment variable
> is set, <path>/<fdtfile> is retrieved. Otherwise, the
> diff --git a/doc/develop/distro.rst b/doc/develop/distro.rst
> index 3ee3dac6a2..bc72aa951e 100644
> --- a/doc/develop/distro.rst
> +++ b/doc/develop/distro.rst
> @@ -68,10 +68,10 @@ Boot Configuration Files
>
> The standard format for boot configuration files is that of extlinux.conf, as
> handled by U-Boot's "syslinux" (disk) or "pxe boot" (network). This is roughly
> -as specified at BootLoaderSpec_:
> +as specified at `Boot Loader Specification`_:
>
>
> -... with the exceptions that the BootLoaderSpec document:
> +... with the exceptions that the Boot Loader Specification document:
>
> * Prescribes a separate configuration per boot menu option, whereas U-Boot
> lumps all options into a single extlinux.conf file. Hence, U-Boot searches
> @@ -81,6 +81,8 @@ as specified at BootLoaderSpec_:
> * Does not document the fdtdir option, which automatically selects the DTB to
> pass to the kernel.
>
> +See also doc/README.pxe under 'pxe file format'.
> +
> One example extlinux.conf generated by the Fedora installer is::
>
> # extlinux.conf generated by anaconda
> @@ -115,6 +117,25 @@ One example extlinux.conf generated by the Fedora installer is::
> fdtdir /boot/dtb-3.16.0-0.rc6.git1.1.fc22.armv7hl+lpae
>
>
> +One example of hand-crafted extlinux.conf::
> +
> + menu title Select kernel
> + timeout 100
> +
> + label Arch with uart devicetree overlay
> + kernel /arch/Image.gz
> + initrd /arch/initramfs-linux.img
> + fdt /dtbs/arch/board.dtb
> + fdtoverlays /dtbs/arch/overlay/uart0-gpio0-1.dtbo
> + append console=ttyS0,115200 console=tty1 rw root=UUID=fc0d0284-ca84-4194-bf8a-4b9da8d66908
> +
> + label Arch with uart devicetree overlay but with Boot Loader Specification keys
> + kernel /arch/Image.gz
> + initrd /arch/initramfs-linux.img
> + devicetree /dtbs/arch/board.dtb
> + devicetree-overlay /dtbs/arch/overlay/uart0-gpio0-1.dtbo
> + append console=ttyS0,115200 console=tty1 rw root=UUID=fc0d0284-ca84-4194-bf8a-4b9da8d66908
> +
> Another hand-crafted network boot configuration file is::
>
> TIMEOUT 100
> @@ -214,6 +235,11 @@ fdt_addr_r:
>
> A size of 1MB for the FDT/DTB seems reasonable.
>
> +fdtoverlay_addr_r:
> + Mandatory. The location in RAM where DTB overlays will be temporarily
> + stored and then applied in the load order to the fdt blob stored at the
> + address indicated in the fdt_addr_r environment variable.
> +
> fdtfile:
> Mandatory. the name of the DTB file for the specific board for instance
> the espressobin v5 board the value is "marvell/armada-3720-espressobin.dtb"
> @@ -408,7 +434,7 @@ way in future u-boot versions. In particular the <device type>_boot
> variables (e.g. mmc_boot, usb_boot) are a strictly internal implementation
> detail and must not be used as a public interface.
>
> -.. _BootLoaderSpec: http://www.freedesktop.org/wiki/Specifications/BootLoaderSpec/
> +.. _`Boot Loader Specification`: https://systemd.io/BOOT_LOADER_SPECIFICATION/
>
> .. sectionauthor:: (C) Copyright 2014 Red Hat Inc.
> .. sectionauthor:: Copyright (c) 2014-2015, NVIDIA CORPORATION. All rights reserved.
Thanks for updating the doc and link to the spec !
Reviewed-by: Neil Armstrong <neil.armstrong at linaro.org>
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