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

[Michael S. Tsirkin]

On Sun, Jul 14, 2013 at 02:27:14PM -0400, Kevin O'Connor wrote:
> 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.

We can do this but what do we do if linker script is there
but no rsdp?
Maybe just add
    test -e /etc/linker-script != RsdpAddr
            dprintf(1, "linker script found but no rsdp. Falling back on builtin tables\n");

Would this address your comment?
> Also, /etc/linker-script is not very informative - how about something
> like "/etc/biostables".
>
> -Kevin

Hmm bios seems redundant, and tables makes one think it's the tables
themselves.

"/etc/acpi-linker"
"/etc/acpi-loader"?