Re: [kvm-unit-tests PATCH] configure: arm/arm64: Add --earlycon option to set UART type and address

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On Fri, Feb 19, 2021 at 04:37:18PM +0000, Alexandru Elisei wrote:
> Currently, the UART early address is set indirectly with the --vmm option
> and there are only two possible values: if the VMM is qemu (the default),
> then the UART address is set to 0x09000000; if the VMM is kvmtool, then the
> UART address is set to 0x3f8.
> 
> There several efforts under way to change the kvmtool UART address, and
> kvm-unit-tests so far hasn't had mechanism to let the user set a specific
> address, which means that the early UART won't be available.
> 
> This situation will only become worse as kvm-unit-tests gains support to
> run as an EFI app, as each platform will have their own UART type and
> address.
> 
> To address both issues, a new configure option is added, --earlycon. The
> syntax and semantics are identical to the kernel parameter with the same
> name. Specifying this option will overwrite the UART address set by --vmm.
> 
> At the moment, the UART type and register width parameters are ignored
> since both qemu's and kvmtool's UART emulation use the same offset for the
> TX register and no other registers are used by kvm-unit-tests, but the
> parameters will become relevant once EFI support is added.
> 
> Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
> ---
> The kvmtool patches I was referring to are the patches to unify ioport and
> MMIO emulation [1] and to allow the user to specify a custom memory layout
> for the VM [2] (these patches are very old, but I plan to revive them after
> the ioport and MMIO unification series are merged).
> 
> [1] https://lore.kernel.org/kvm/20201210142908.169597-1-andre.przywara@xxxxxxx/T/#t
> [2] https://lore.kernel.org/kvm/1569245722-23375-1-git-send-email-alexandru.elisei@xxxxxxx/
> 
>  configure | 35 +++++++++++++++++++++++++++++++++++
>  1 file changed, 35 insertions(+)
> 
> diff --git a/configure b/configure
> index cdcd34e94030..d94b92255088 100755
> --- a/configure
> +++ b/configure
> @@ -26,6 +26,7 @@ errata_force=0
>  erratatxt="$srcdir/errata.txt"
>  host_key_document=
>  page_size=
> +earlycon=
>  
>  usage() {
>      cat <<-EOF
> @@ -54,6 +55,17 @@ usage() {
>  	    --page-size=PAGE_SIZE
>  	                           Specify the page size (translation granule) (4k, 16k or
>  	                           64k, default is 64k, arm64 only)
> +	    --earlycon=EARLYCON
> +	                           Specify the UART name, type and address (optional, arm and
> +	                           arm64 only). The specified address will overwrite the UART
> +	                           address set by the --vmm option. EARLYCON can be on of (case

s/be on of/be one of/

> +	                           sensitive):
> +	               uart[8250],mmio,ADDR
> +	                           Specify an 8250 compatible UART at address ADDR. Supported
> +	                           register stride is 8 bit only.
> +	               pl011,mmio,ADDR
> +	                           Specify a PL011 compatible UART at address ADDR. Supported
> +	                           register stride is 8 bit only.
>  EOF
>      exit 1
>  }
> @@ -112,6 +124,9 @@ while [[ "$1" = -* ]]; do
>  	--page-size)
>  	    page_size="$arg"
>  	    ;;
> +	--earlycon)
> +	    earlycon="$arg"
> +	    ;;
>  	--help)
>  	    usage
>  	    ;;
> @@ -170,6 +185,26 @@ elif [ "$arch" = "arm" ] || [ "$arch" = "arm64" ]; then
>          echo '--vmm must be one of "qemu" or "kvmtool"!'
>          usage
>      fi
> +
> +    if [ "$earlycon" ]; then
> +        name=$(echo $earlycon|cut -d',' -f1)
> +        if [ "$name" != "uart" ] && [ "$name" != "uart8250" ] &&
> +                [ "$name" != "pl011" ]; then
> +            echo "unknown earlycon name: $name"
> +            usage
> +        fi
> +        type=$(echo $earlycon|cut -d',' -f2)
> +        if [ "$type" != "mmio" ]; then
> +            echo "unknown earlycon type: $type"
> +            usage
> +        fi
> +        addr=$(echo $earlycon|cut -d',' -f3)
> +        if [ -z "$addr" ]; then
> +            echo "missing earlycon address"
> +            usage
> +        fi
> +        arm_uart_early_addr=$addr
> +    fi
>  elif [ "$arch" = "ppc64" ]; then
>      testdir=powerpc
>      firmware="$testdir/boot_rom.bin"
> -- 
> 2.30.1
>

Otherwise,
 
Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx>

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