Re: [Xen-devel] [PATCH v4 05/16] libxl/arm: Construct ACPI RSDP table

[Julien Grall <julien.grall@xxxxxxx>]

Hi Shannon,

On 16/08/2016 06:25, Shannon Zhao wrote:
> From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
>
> Construct ACPI RSDP table and add a helper to calculate the ACPI table
> checksum.
>
> Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
> ---
>  tools/libxl/libxl_arm_acpi.c | 38 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
>
> diff --git a/tools/libxl/libxl_arm_acpi.c b/tools/libxl/libxl_arm_acpi.c
> index 6be9eb0..9432e44 100644
> --- a/tools/libxl/libxl_arm_acpi.c
> +++ b/tools/libxl/libxl_arm_acpi.c
> @@ -33,6 +33,9 @@ extern const unsigned char dsdt_anycpu_arm[];
>  _hidden
>  extern const int dsdt_anycpu_arm_len;
>
> +#define ACPI_BUILD_APPNAME6 "XenARM"
> +#define ACPI_BUILD_APPNAME4 "Xen "
> +
>  enum {
>      RSDP,
>      XSDT,
> @@ -112,6 +115,37 @@ out:
>      return rc;
>  }
>
> +static void calculate_checksum(void *table, uint32_t checksum_offset,
> +                               uint32_t length)
> +{
> +    uint8_t *p, sum = 0;
> +
> +    p = table;
> +    p[checksum_offset] = 0;
> +
> +    while ( length-- )
> +        sum = sum + *p++;
> +
> +    p = table;
> +    p[checksum_offset] = -sum;
> +}
> +
> +static void make_acpi_rsdp(libxl__gc *gc, struct xc_dom_image *dom,
> +                           struct acpitable acpitables[])
> +{
> +    uint64_t offset = acpitables[RSDP].addr - GUEST_ACPI_BASE;
> +    struct acpi_table_rsdp *rsdp = (void *)dom->acpi_modules[0].data + offset;
Why do you cast to (void *)?

> +
> +    memcpy(rsdp->signature, "RSD PTR ", sizeof(rsdp->signature));
> +    memcpy(rsdp->oem_id, ACPI_BUILD_APPNAME6, sizeof(rsdp->oem_id));
> +    rsdp->length = acpitables[RSDP].size;
> +    rsdp->revision = 0x02;
> +    rsdp->xsdt_physical_address = acpitables[XSDT].addr;
> +    calculate_checksum(rsdp,
> +                       offsetof(struct acpi_table_rsdp, extended_checksum),
> +                       acpitables[RSDP].size);
> +}
> +
>  int libxl__prepare_acpi(libxl__gc *gc, libxl_domain_build_info *info,
>                          libxl__domain_build_state *state,
>                          struct xc_dom_image *dom)
> @@ -137,6 +171,10 @@ int libxl__prepare_acpi(libxl__gc *gc, 
> libxl_domain_build_info *info,
>      dom->acpi_modules[0].guest_addr_out = GUEST_ACPI_BASE;
>
>      rc = libxl__estimate_acpi_size(gc, info, dom, xc_config, acpitables);
> +    if (rc)
> +        goto out;
> +
> +    make_acpi_rsdp(gc, dom, acpitables);
>
>  out:
>      return rc;
--
Julien Grall

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