Re: [PATCH v3 03/35] acpi: build_xsdt: use acpi_table_begin()/acpi_table_end() instead of build_header()

[Eric Auger]

Hi,

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.
> 
> While at it switch to build_append_int_noprefix() to build
> entries to other tables (which also removes some manual offset
> calculations).
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>

> ---
> v3:
>   * s/acpi_init_table|acpi_table_composed/acpi_table_begin|acpi_table_end/
> ---
>  include/hw/acpi/acpi-defs.h | 10 ----------
>  hw/acpi/aml-build.c         | 27 ++++++++++++---------------
>  2 files changed, 12 insertions(+), 25 deletions(-)
> 
> diff --git a/include/hw/acpi/acpi-defs.h b/include/hw/acpi/acpi-defs.h
> index ccfa3382aa..f6d2ca172b 100644
> --- a/include/hw/acpi/acpi-defs.h
> +++ b/include/hw/acpi/acpi-defs.h
> @@ -149,16 +149,6 @@ struct AcpiSerialPortConsoleRedirection {
>  typedef struct AcpiSerialPortConsoleRedirection
>                 AcpiSerialPortConsoleRedirection;
>  
> -/*
> - * ACPI 2.0 eXtended System Description Table (XSDT)
nit: you may move that comment to aml-build.c

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

Eric
> - */
> -struct AcpiXsdtDescriptorRev2 {
> -    ACPI_TABLE_HEADER_DEF       /* ACPI common table header */
> -    uint64_t table_offset_entry[];  /* Array of pointers to other */
> -    /* ACPI tables */
> -} QEMU_PACKED;
> -typedef struct AcpiXsdtDescriptorRev2 AcpiXsdtDescriptorRev2;
> -
>  /*
>   * ACPI 1.0 Firmware ACPI Control Structure (FACS)
>   */
> diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
> index 32f14d4a78..daefc132f3 100644
> --- a/hw/acpi/aml-build.c
> +++ b/hw/acpi/aml-build.c
> @@ -1916,27 +1916,24 @@ build_xsdt(GArray *table_data, BIOSLinker *linker, 
> GArray *table_offsets,
>             const char *oem_id, const char *oem_table_id)
>  {
>      int i;
> -    unsigned xsdt_entries_offset;
> -    AcpiXsdtDescriptorRev2 *xsdt;
> -    int xsdt_start = table_data->len;
> -    const unsigned table_data_len = (sizeof(uint64_t) * table_offsets->len);
> -    const unsigned xsdt_entry_size = sizeof(xsdt->table_offset_entry[0]);
> -    const size_t xsdt_len = sizeof(*xsdt) + table_data_len;
> -
> -    xsdt = acpi_data_push(table_data, xsdt_len);
> -    xsdt_entries_offset = (char *)xsdt->table_offset_entry - 
> table_data->data;
> +    AcpiTable table = { .sig = "XSDT", .rev = 1,
> +                        .oem_id = oem_id, .oem_table_id = oem_table_id };
> +
> +    acpi_table_begin(&table, table_data);
> +
>      for (i = 0; i < table_offsets->len; ++i) {
>          uint64_t ref_tbl_offset = g_array_index(table_offsets, uint32_t, i);
> -        uint64_t xsdt_entry_offset = xsdt_entries_offset + xsdt_entry_size * 
> i;
> +        uint64_t xsdt_entry_offset = table.array->len;
>  
> -        /* xsdt->table_offset_entry to be filled by Guest linker */
> +        /* reserve space for entry */
> +        build_append_int_noprefix(table.array, 0, 8);
> +
> +        /* mark position of RSDT entry to be filled by Guest linker */
>          bios_linker_loader_add_pointer(linker,
> -            ACPI_BUILD_TABLE_FILE, xsdt_entry_offset, xsdt_entry_size,
> +            ACPI_BUILD_TABLE_FILE, xsdt_entry_offset, 8,
>              ACPI_BUILD_TABLE_FILE, ref_tbl_offset);
>      }
> -    build_header(linker, table_data,
> -                 (void *)(table_data->data + xsdt_start),
> -                 "XSDT", xsdt_len, 1, oem_id, oem_table_id);
> +    acpi_table_end(linker, &table);
>  }
>  
>  void build_srat_memory(AcpiSratMemoryAffinity *numamem, uint64_t base,
>