Re: [Xen-devel] [RFC PATCH 10/12] libacpi: build ACPI MCFG table if requested

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 12.03.18 at 19:33, <x1917x@xxxxxxxxx> wrote:
> --- a/tools/libacpi/acpi2_0.h
> +++ b/tools/libacpi/acpi2_0.h
> @@ -422,6 +422,25 @@ struct acpi_20_slit {
>  };
>  
>  /*
> + * PCI Express Memory Mapped Configuration Description Table
> + */
> +struct mcfg_range_entry {
> +    uint64_t base_address;
> +    uint16_t pci_segment;
> +    uint8_t  start_pci_bus_num;
> +    uint8_t  end_pci_bus_num;
> +    uint32_t reserved;
> +};
> +
> +struct acpi_mcfg {
> +    struct acpi_header header;
> +    uint8_t reserved[8];
> +    struct mcfg_range_entry entries[1];
> +};
> +
> +#define MCFG_SIZE_TO_NUM_BUSES(size)  ((size) >> 20)

In a response to a comment from Roger you suggested to move this to pci_regs.h.
I don't see why it would belong there. I think if ACPI spells out such a formula
somewhere, it's fine to liver here. Otherwise, since you need it in a single 
file only,
please put it into the .c file.

> --- a/tools/libacpi/build.c
> +++ b/tools/libacpi/build.c
> @@ -303,6 +303,37 @@ static struct acpi_20_slit *construct_slit(struct 
> acpi_ctxt *ctxt,
>      return slit;
>  }
>  
> +static struct acpi_mcfg *construct_mcfg(struct acpi_ctxt *ctxt,
> +                                        const struct acpi_config *config)
> +{
> +    struct acpi_mcfg *mcfg;
> +
> +    /* Warning: this code expects that we have only one PCI segment */
> +    mcfg = ctxt->mem_ops.alloc(ctxt, sizeof(*mcfg), 16);
> +    if (!mcfg)
> +        return NULL;
> +
> +    memset(mcfg, 0, sizeof(*mcfg));
> +    mcfg->header.signature    = ACPI_MCFG_SIGNATURE;
> +    mcfg->header.revision     = ACPI_1_0_MCFG_REVISION;
> +    fixed_strcpy(mcfg->header.oem_id, ACPI_OEM_ID);
> +    fixed_strcpy(mcfg->header.oem_table_id, ACPI_OEM_TABLE_ID);
> +    mcfg->header.oem_revision = ACPI_OEM_REVISION;
> +    mcfg->header.creator_id   = ACPI_CREATOR_ID;
> +    mcfg->header.creator_revision = ACPI_CREATOR_REVISION;
> +    mcfg->header.length = sizeof(*mcfg);
> +
> +    mcfg->entries[0].base_address = config->mmconfig_addr;
> +    mcfg->entries[0].pci_segment = 0;
> +    mcfg->entries[0].start_pci_bus_num = 0;
> +    mcfg->entries[0].end_pci_bus_num =
> +        MCFG_SIZE_TO_NUM_BUSES(config->mmconfig_len) - 1;
> +
> +    set_checksum(mcfg, offsetof(struct acpi_header, checksum), 
> sizeof(*mcfg));

Despite the numerous pre-existing examples this isn't really correct.
What you mean is something like

    set_checksum(mcfg, offsetof(typeof(*mcfg), header.checksum), sizeof(*mcfg));

Jan



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