Re: [PATCH v5 01/11] hw: arm: Add bananapi M2-Ultra and allwinner-r40 support

[qianfan]

在 2023/6/18 0:29, Guenter Roeck 写道:
> Hi,
>
> On Tue, May 23, 2023 at 06:04:58PM +0800, qianfanguijin@163.com wrote:
> > From: qianfan Zhao <qianfanguijin@163.com>
> >
> > Allwinner R40 (sun8i) SoC features a Quad-Core Cortex-A7 ARM CPU,
> > and a Mali400 MP2 GPU from ARM. It's also known as the Allwinner T3
> > for In-Car Entertainment usage, A40i and A40pro are variants that
> > differ in applicable temperatures range (industrial and military).
> >
> > Signed-off-by: qianfan Zhao <qianfanguijin@163.com>
> > Reviewed-by: Niek Linnenbank <nieklinnenbank@gmail.com>
> I tried this in mainline linux with the following command.
>
> qemu-system-arm -M bpim2u \
>         -kernel arch/arm/boot/zImage -no-reboot \
>         -snapshot -drive file=rootfs-armv7a.ext2,format=raw,if=sd \
>         -nic user \
>         --append "root=/dev/mmcblk0 rootwait console=ttyS0,115200" \
>         -dtb arch/arm/boot/dts/sun8i-r40-bananapi-m2-ultra.dtb \
>         -nographic -monitor null -serial stdio
>
> Main problem is that the SD card gets instantiated randomly to
> mmc0, mmc1, or mmc2, making it all but impossible to specify a
> root file system device. The non-instantiated cards are always
> reported as non-removable, including mmc0. Example:
>
> mmc0: Failed to initialize a non-removable card
>
> Using "-sd <file>" instead of "-drive file=<file>" does not
> make a difference.
>
> I can fix (work around ?) the problem by adding the following information
> to the devicetree file.
>
>          aliases {
>                  ethernet0 = &gmac;
>                  serial0 = &uart0;
> +               mmc0 = &mmc0;
> +               mmc1 = &mmc1;
> +               mmc2 = &mmc2;
>          };
>
> Linux upstream commits fa2d0aa96941 and 2a43322ca7f3 describe the
> logic behind this change.
>
> Is this a bug in the Linux kernel, or a problem with the qemu emulation ?

On my work, the linux kenrel doesn't startup ext4 rootfs directly, it start

a custom ramdisk and we can handle this in ramdisk scripts.

> Either case, is there a way to specify a qemu command line that doesn't
> result in random assignments of the provided drive to mmc0/1/2 ?
>
> Thanks,
> Guenter