Re: [PATCH 2/2] xen, rpi4: Use PARTUUID for rootfs discovery

Christopher Clark

On Thu, Sep 30, 2021 at 8:03 AM Bertrand Marquis <bertrand.marquis@...> wrote:
Hi Luca,

> On 30 Sep 2021, at 15:54, Luca Fancellu <Luca.Fancellu@...> wrote:
> The mmc probing order has become unpredictable
> due to recent linux kernel changes, therefore devices
> like the raspberry pi that have two mmc interface most
> of the time can't boot from the hard-coded root path.
> Modify the u-boot script to fetch the PARTUUID of the
> second partition of the sd card and use it to put
> root=PARTUUID=<xxx> in the command line passed to
> the dom0 kernel.

Thanks for posting a way of handling this. I've encountered the same unpredictable device enumeration and had been looking into whether switching the sdhci_iproc driver to PROBE_FORCE_SYNCHRONOUS instead of PROBE_PREFER_ASYNCHRONOUS would resolve it but I can't report that it does. I would prefer to have a way to get stable enumeration but without it, this is an improvement.
> Signed-off-by: Luca Fancellu <luca.fancellu@...>
> Reviewed-by: Diego Sueiro <diego.sueiro@...
Reviewed-by: Bertrand Marquis <bertrand.marquis@...>

Reviewed-by: Christopher Clark <christopher.w.clark@...>
Tested-by: Christopher Clark <christopher.w.clark@...>




> ---
> .../xen-rpi-u-boot-scr/files/          | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
> diff --git a/dynamic-layers/raspberrypi/recipes-bsp/xen-rpi-u-boot-scr/files/ b/dynamic-layers/raspberrypi/recipes-bsp/xen-rpi-u-boot-scr/files/
> index 0367e36..9874220 100644
> --- a/dynamic-layers/raspberrypi/recipes-bsp/xen-rpi-u-boot-scr/files/
> +++ b/dynamic-layers/raspberrypi/recipes-bsp/xen-rpi-u-boot-scr/files/
> @@ -13,10 +13,6 @@ fdt resize 0x1000
> echo Add boot arguments for Xen
> fdt set /chosen xen,xen-bootargs "console=dtuart dtuart=/soc/serial@7e215040 dom0_mem='@@RPI_DOM0_MEM@@' @@RPI_DEBUG_XEN_ARGS@@"
> -echo Add boot arguments for dom0
> -setenv dom0_bootargs "console=hvc0 earlycon=xenboot debug root=/dev/mmcblk0p2 rootwait"
> -fdt set /chosen xen,dom0-bootargs \"${dom0_bootargs}\"
> -
> echo Add a dom0 node to chosen to put Linux boot information in
> fdt mknode /chosen dom0
> @@ -32,6 +28,13 @@ fdt rm /scb/pcie@7d500000/pci@1,0/usb@1,0
> echo Delay to allow the MMC card to be ready
> sleep 1
> +# Retrieve PARTUUID for the rootfs partition of the sdcard
> +part uuid mmc 1:2 rootfs_partuuid
> +
> +echo Add boot arguments for dom0
> +setenv dom0_bootargs "console=hvc0 earlycon=xenboot debug root=PARTUUID=${rootfs_partuuid} rootwait"
> +fdt set /chosen xen,dom0-bootargs \"${dom0_bootargs}\"
> +
> echo Load Xen into memory
> fatload mmc 1:1 ${xen_loadaddr} xen
> echo Xen loaded, size: 0x$filesize
> --
> 2.17.1

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