Re: [SeaBIOS] [PATCH v2 4/5] acpi: load and link tables from /etc/acpi/

[Kevin O'Connor]

On Sun, Jul 07, 2013 at 06:42:43PM +0300, Michael S. Tsirkin wrote:
> Load files in /etc/acpi/, link them using
> a linker script and use for acpi tables, including the RSDP.
> Presense of RSDP in this directory completely disables
> generating and loading legacy acpi tables.
> Signed-off-by: Michael S. Tsirkin
>
> src/acpi.c | 39 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 39 insertions(+)
>
> diff --git a/src/acpi.c b/src/acpi.c
> index a81f0cb..07d311a 100644
> --- a/src/acpi.c
> +++ b/src/acpi.c
> @@ -27,6 +27,7 @@
>  #include "config.h" // CONFIG_*
>  #include "paravirt.h" // RamSize
>  #include "dev-q35.h"
> +#include "linker.h"
>
> #include "acpi-dsdt.hex"
>
> @@ -599,6 +600,34 @@ static const struct pci_device_id acpi_find_tbl[] = {
>
> struct rsdp_descriptor *RsdpAddr;
>
> +/* Look for RSDP signature in files loaded in FSEG */
> +struct rsdp_descriptor *
> +acpi_find_rsdp_rom(void)
> +{
> struct romfile_s *file = NULL;
> struct rsdp_descriptor *rsdp = NULL;
> for (;;) {
>    file = romfile_findprefix("", file);
>    if (!file)
>        break;
>    if (!file->data || !pmm_test_fseg(file->data) ||
>        file->size < sizeof(rsdp->signature))
>        continue;
>    void *data;
>    for (data = file->data;
>         data + sizeof(*rsdp) <= file->data + file->size;
>         data++) {
>        rsdp = data;
>        if (rsdp->signature == cpu_to_le64(RSDP_SIGNATURE))
>            return rsdp;
>    }
> }
> return NULL;
>
> +}
>
> #define MAX_ACPI_TABLES 20
>  void
>  acpi_setup(void)
> @@ -608,6 +637,16 @@ acpi_setup(void)
>  dprintf(3, "init ACPI tables\n");
>
> linker_loader_execute("/etc/linker-script");
> RsdpAddr = acpi_find_rsdp_rom();
> if (RsdpAddr) {
>    return;
> }

I don't understand this.  Why not use the presence of
"/etc/linker-script" to determine if ACPI should be produced.

Also, /etc/linker-script is not very informative - how about something
like "/etc/biostables".

-Kevin