Re: [PATCH v5 19/19] libxl: build a device tree for ARM guests

[Julien Grall <julien.grall@linaro.org>]

On 11/13/2013 06:11 PM, Ian Campbell wrote:
> Uses xc_dom_devicetree_mem which was just added. The call to this needs to be
> carefully sequenced to be after xc_dom_parse_image (so we can tell which kind
> of guest we are building, although we don't use this yet) and before
> xc_dom_mem_init which tries to decide where to place the FDT in guest RAM.
>
> Removes libxl_noarch which would only have been used by IA64 after this
> change. Remove IA64 as part of this patch.
>
> There is no attempt to expose this as a configuration setting for the user.
>
> Includes a debug hook to dump the dtb to a file for inspection.
>
> TODO:
> - v7 CPU compat is hardcoded to cortex-a15 -- may need to define something more
>    generic via mach-virt dt bindngs?
>
> Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
> Cc: Ian Jackson <ian.jackson@eu.citrix.com>
> ---
> v5: Correct error handling in debug_dump_fdt
> v4: Drop spurious comment in header
>      s/__be32/be32/ and s/gic_interrupt_t/gic_interrupt/ to avoid reserved names
>      Coding style fixes
>      Use GCSPRINTF
>      use for(;;) around FDT creation loop, undef FDT when done
>      use libxl__realloc for fdt size increase
>      Refactor debug dump into its own function, remove NDEBUG ifdef
> v2: base addresses, irq, evtchn etc stuff is now from public API headers,
>      avoiding the need to introduce domctls etc until we want to make them
>      dynamic.
>      fix memory node
>      Improve libfdt error handling, especially for FDT_ERR_NOSPACE.
>      Derive guest CPU and timer compatiblity nodes from the guest type.
>
> wip
> ---
>   tools/libxl/Makefile       |    6 +-
>   tools/libxl/libxl_arch.h   |    3 +
>   tools/libxl/libxl_arm.c    |  512 ++++++++++++++++++++++++++++++++++++++++++++
>   tools/libxl/libxl_dom.c    |    4 +
>   tools/libxl/libxl_noarch.c |    8 -
>   tools/libxl/libxl_x86.c    |    7 +
>   6 files changed, 530 insertions(+), 10 deletions(-)
>   create mode 100644 tools/libxl/libxl_arm.c
>   delete mode 100644 tools/libxl/libxl_noarch.c
>

[..]

> +    for (;;) {
> +next_resize:
> +        if (fdt_size) {
> +            fdt_size <<= 1;
> +            LOG(DEBUG, "Increasing FDT size to %zd and retrying", fdt_size);
> +        } else {
> +            fdt_size = 4096;
> +        }
> +
> +        fdt = libxl__realloc(gc, fdt, fdt_size);
> +
> +        FDT( fdt_create(fdt, fdt_size) );
> +
> +        FDT( fdt_finish_reservemap(fdt) );
> +
> +        FDT( fdt_begin_node(fdt, "") );
> +
> +        FDT( make_root_properties(gc, vers, fdt) );
> +        FDT( make_chosen_node(gc, fdt, info) );
> +        FDT( make_cpus_node(gc, fdt, info->max_vcpus, ainfo) );
> +        FDT( make_psci_node(gc, fdt) );
> +
> +        FDT( make_memory_node(gc, fdt,
> +                              dom->rambase_pfn << XC_PAGE_SHIFT,
> +                              info->target_memkb * 1024) );
> +        FDT( make_intc_node(gc, fdt,
> +                            GUEST_GICD_BASE, GUEST_GICD_SIZE,
> +                            GUEST_GICC_BASE, GUEST_GICD_SIZE) );
> +
> +        FDT( make_timer_node(gc, fdt, ainfo) );
> +        FDT( make_hypervisor_node(gc, fdt, vers) );
> +
> +        FDT( fdt_end_node(fdt) );
> +
> +        FDT( fdt_finish(fdt) );
> +        break;
> +    }
> +#undef FDT

Why didn't you try to use fdt_open_into? It should fit our usage: ie, 
grow up the size of the device tree. Actually, DTC uses this solution 
when the fdt needs to be resized.

-- 
Julien Grall