Re: [Minios-devel] [UNIKRAFT PATCHv5 35/46] plat/kvm: Parse command line from device tree for Arm64

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

This code is from arm32 Xen port, right? It looks familiar to me. ;-)

Reviewed-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>

On 10.08.2018 09:08, Wei Chen wrote:
> From: Wei Chen <Wei.Chen@xxxxxxx>
>
> Device tree has a "chosen" node, this node can be used to pass
> parameters to virtual machine through bootargs property. We can
> use this feature to pass command line to unikraft application,
> and then parse it from device tree for further usage.
>
> The command line will be modified in uk_argparse, but the memory
> attribute of DTB is readonly, we need a copy of this command line.
>
> Signed-off-by: Wei Chen <Wei.Chen@xxxxxxx>
> ---
>   plat/kvm/arm/setup.c | 32 ++++++++++++++++++++++++++++++++
>   1 file changed, 32 insertions(+)
>
> diff --git a/plat/kvm/arm/setup.c b/plat/kvm/arm/setup.c
> index aca3444..d59956a 100644
> --- a/plat/kvm/arm/setup.c
> +++ b/plat/kvm/arm/setup.c
> @@ -24,6 +24,9 @@
>   
>   void *_libkvmplat_dtb;
>   
> +#define MAX_CMDLINE_SIZE 1024
> +static char cmdline[MAX_CMDLINE_SIZE];
> +
>   static void _init_dtb(void *dtb_pointer)
>   {
>         int ret;
> @@ -35,10 +38,39 @@ static void _init_dtb(void *dtb_pointer)
>         uk_printd(DLVL_INFO, "Found device tree on: %p\n", dtb_pointer);
>   }
>   
> +static void _dtb_get_cmdline(char *cmdline, size_t maxlen)
> +{
> +       int fdtchosen, len;
> +       const char *fdtcmdline;
> +
> +       /* TODO: Proper error handling */
> +       fdtchosen = fdt_path_offset(_libkvmplat_dtb, "/chosen");
> +       if (!fdtchosen)
> +               goto enocmdl;
> +       fdtcmdline = fdt_getprop(_libkvmplat_dtb, fdtchosen, "bootargs", &len);
> +       if (!fdtcmdline || (len <= 0))
> +               goto enocmdl;
> +
> +       strncpy(cmdline, fdtcmdline, MIN(maxlen, (unsigned int) len));
> +       /* ensure null termination */
> +       cmdline[((unsigned int) len - 1) <= (maxlen - 1) ?
> +               ((unsigned int) len - 1) : (maxlen - 1)] = '\0';
> +
> +       uk_printd(DLVL_INFO, "Command line: %s\n", cmdline);
> +       return;
> +
> +enocmdl:
> +       uk_printd(DLVL_INFO, "No command line found\n");
> +       strcpy(cmdline, CONFIG_UK_NAME);
> +}
> +
>   void _libkvmplat_start(void *dtb_pointer)
>   {
>         _init_dtb(dtb_pointer);
>         _libkvmplat_init_console();
>   
>   	uk_printd(DLVL_INFO, "Entering from KVM (arm64)...\n");
> +
> +       /* Get command line from DTB */
> +       _dtb_get_cmdline(cmdline, sizeof(cmdline));
>   }
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