Re: [PATCH v3 11/35] acpi: nvdimm_build_ssdt: use acpi_table_begin()/acpi_table_end() instead of build_header()

[Eric Auger]

Hi Igor,

On 9/7/21 4:47 PM, Igor Mammedov wrote:
> it replaces error-prone pointer arithmetic for build_header() API,
> with 2 calls to start and finish table creation,
> which hides offsets magic from API user.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> ---
> v3:
>   * s/acpi_init_table|acpi_table_composed/acpi_table_begin|acpi_table_end/
> 
> CC: xiaoguangrong.eric@gmail.com
> ---
>  hw/acpi/nvdimm.c | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c
> index 15f6ca82ca..e050b47c2b 100644
> --- a/hw/acpi/nvdimm.c
> +++ b/hw/acpi/nvdimm.c
> @@ -1274,14 +1274,15 @@ static void nvdimm_build_ssdt(GArray *table_offsets, 
> GArray *table_data,
>                                NVDIMMState *nvdimm_state,
>                                uint32_t ram_slots, const char *oem_id)
>  {
> +    int mem_addr_offset;
>      Aml *ssdt, *sb_scope, *dev;
> -    int mem_addr_offset, nvdimm_ssdt;
> +    AcpiTable table = { .sig = "SSDT", .rev = 1,
> +                        .oem_id = oem_id, .oem_table_id = "NVDIMM" };
>  
>      acpi_add_table(table_offsets, table_data);
>  
> +    acpi_table_begin(&table, table_data);
>      ssdt = init_aml_allocator();
> -    acpi_data_push(ssdt->buf, sizeof(AcpiTableHeader));
> -
>      sb_scope = aml_scope("\\_SB");
>  
>      dev = aml_device("NVDR");
> @@ -1310,8 +1311,6 @@ static void nvdimm_build_ssdt(GArray *table_offsets, 
> GArray *table_data,
>      aml_append(sb_scope, dev);
>      aml_append(ssdt, sb_scope);
>  
> -    nvdimm_ssdt = table_data->len;
> -
>      /* copy AML table into ACPI tables blob and patch header there */
>      g_array_append_vals(table_data, ssdt->buf->data, ssdt->buf->len);
>      mem_addr_offset = build_append_named_dword(table_data,
> @@ -1323,10 +1322,13 @@ static void nvdimm_build_ssdt(GArray *table_offsets, 
> GArray *table_data,
>      bios_linker_loader_add_pointer(linker,
>          ACPI_BUILD_TABLE_FILE, mem_addr_offset, sizeof(uint32_t),
>          NVDIMM_DSM_MEM_FILE, 0);
> -    build_header(linker, table_data,
> -        (void *)(table_data->data + nvdimm_ssdt),
> -                 "SSDT", table_data->len - nvdimm_ssdt, 1, oem_id, "NVDIMM");
>      free_aml_allocator();
> +    /*
> +     * must be executed as the last so that pointer patching command above
> +     * would be executed by guest before it recalculates checksum which were
> +     * scheduled by acpi_table_composed()
s/acpi_table_composed/acpi_table_end.

also the sentence may need some rewording.

Wonder if that kind of comment still is useful. Maybe this should be put
once in the doc comment of acpi_table_end() in [PATCH v3 01/35] acpi:
add helper routines to initialize ACPI tables, for future users to pay
attention that it shall be called at the very end.

Besides

Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric


> +     */
> +    acpi_table_end(linker, &table);
>  }
>  
>  void nvdimm_build_srat(GArray *table_data)
>