Re: [Qemu-devel] [PATCH 4/8] hw: arm: Carry RSDP specific data through AcpiRsdpData

[Samuel Ortiz <sameo@linux.intel.com>]

Hi Igor,

On Tue, Nov 27, 2018 at 04:25:51PM +0100, Igor Mammedov wrote:
> On Mon, 26 Nov 2018 17:29:37 +0100
> Samuel Ortiz <sameo@linux.intel.com> wrote:
> 
> > That will allow us to generalize the ARM build_rsdp() routine to support
> > both legacy RSDP (The current i386 implementation) and extended RSDP
> > (The ARM implementation).
> > 
> > Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
> > ---
> >  include/hw/acpi/acpi-defs.h | 11 +++++++++++
> >  hw/arm/virt-acpi-build.c    | 27 ++++++++++++++++++++++-----
> >  2 files changed, 33 insertions(+), 5 deletions(-)
> > 
> > diff --git a/include/hw/acpi/acpi-defs.h b/include/hw/acpi/acpi-defs.h
> > index af8e023968..e7fd24c6c5 100644
> > --- a/include/hw/acpi/acpi-defs.h
> > +++ b/include/hw/acpi/acpi-defs.h
> > @@ -53,6 +53,17 @@ struct AcpiRsdpDescriptor {        /* Root System Descriptor Pointer */
> >  } QEMU_PACKED;
> >  typedef struct AcpiRsdpDescriptor AcpiRsdpDescriptor;
> >  
> > +typedef struct AcpiRsdpData {
> > +    uint8_t oem_id[6]; /* OEM identification */
> > +    uint8_t revision;  /* Must be 0 for 1.0, 2 for 2.0 */
> > +
> > +    unsigned *rsdt_tbl_offset;
> > +    unsigned *xsdt_tbl_offset;
> > +} AcpiRsdpData;
> > +
> 
> > +#define ACPI_RSDP_REV_1 0
> > +#define ACPI_RSDP_REV_2 2
> it's one time used spec defined values so just use values directly
> in place with a comment, so reader won't have to jump around code
> when comparing to spec.
It's also used in the ACPI tests fix patch.
Also the 0 for revision 1 is a little confusing, I feel the above
definition is clearer.


> > +
> >  /* Table structure from Linux kernel (the ACPI tables are under the
> >     BSD license) */
> >  
> > diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> > index 0835900052..2dad465ecf 100644
> > --- a/hw/arm/virt-acpi-build.c
> > +++ b/hw/arm/virt-acpi-build.c
> > @@ -368,7 +368,7 @@ static void acpi_dsdt_add_power_button(Aml *scope)
> >  
> >  /* RSDP */
> >  static void
> > -build_rsdp(GArray *rsdp_table, BIOSLinker *linker, unsigned xsdt_tbl_offset)
> > +build_rsdp(GArray *rsdp_table, BIOSLinker *linker, AcpiRsdpData *rsdp_data)
> >  {
> >      AcpiRsdpDescriptor *rsdp = acpi_data_push(rsdp_table, sizeof *rsdp);
> >      unsigned xsdt_pa_size = sizeof(rsdp->xsdt_physical_address);
> > @@ -379,14 +379,14 @@ build_rsdp(GArray *rsdp_table, BIOSLinker *linker, unsigned xsdt_tbl_offset)
> >                               true /* fseg memory */);
> >  
> >      memcpy(&rsdp->signature, "RSD PTR ", sizeof(rsdp->signature));
> > -    memcpy(rsdp->oem_id, ACPI_BUILD_APPNAME6, sizeof(rsdp->oem_id));
> > +    memcpy(rsdp->oem_id, rsdp_data->oem_id, sizeof(rsdp->oem_id));
> >      rsdp->length = cpu_to_le32(sizeof(*rsdp));
> > -    rsdp->revision = 0x02;
> > +    rsdp->revision = rsdp_data->revision;
> >  
> >      /* Address to be filled by Guest linker */
> >      bios_linker_loader_add_pointer(linker,
> >          ACPI_BUILD_RSDP_FILE, xsdt_pa_offset, xsdt_pa_size,
> > -        ACPI_BUILD_TABLE_FILE, xsdt_tbl_offset);
> > +        ACPI_BUILD_TABLE_FILE, *rsdp_data->xsdt_tbl_offset);
> >  
> >      /* Checksum to be filled by Guest linker */
> >      bios_linker_loader_add_checksum(linker, ACPI_BUILD_RSDP_FILE,
> > @@ -399,6 +399,20 @@ build_rsdp(GArray *rsdp_table, BIOSLinker *linker, unsigned xsdt_tbl_offset)
> >          (char *)&rsdp->extended_checksum - rsdp_table->data);
> >  }
> >  
> > +static void
> > +init_rsdp_data(AcpiRsdpData *data, const char *oem_id, uint8_t revision,
> > +               unsigned *rsdt_offset, unsigned *xsdt_offset)
> > +{
> > +    /* Caller must provide an OEM ID */
> > +    g_assert(oem_id);
> > +    g_assert(strlen(oem_id) >= 6);
> > +
> > +    memcpy(data->oem_id, oem_id, 6);
> > +    data->revision = revision;
> > +    data->rsdt_tbl_offset = rsdt_offset;
> > +    data->xsdt_tbl_offset = xsdt_offset;
> > +}
> > +
> >  static void
> >  build_iort(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
> >  {
> > @@ -810,6 +824,7 @@ void virt_acpi_build(VirtMachineState *vms, AcpiBuildTables *tables)
> >      GArray *table_offsets;
> >      unsigned dsdt, xsdt;
> >      GArray *tables_blob = tables->table_data;
> > +    AcpiRsdpData rsdp;
> s/rsdp/rsdp_info/
> 
> >  
> >      table_offsets = g_array_new(false, true /* clear */,
> >                                          sizeof(uint32_t));
> > @@ -857,7 +872,9 @@ void virt_acpi_build(VirtMachineState *vms, AcpiBuildTables *tables)
> >      build_xsdt(tables_blob, tables->linker, table_offsets, NULL, NULL);
> >  
> >      /* RSDP is in FSEG memory, so allocate it separately */
> > -    build_rsdp(tables->rsdp, tables->linker, xsdt);
> > +    init_rsdp_data(&rsdp, ACPI_BUILD_APPNAME6, ACPI_RSDP_REV_2,
> > +                   NULL, &xsdt);
> It would be more concise to use declarative style without extra clutter:
> 
> -    init_rsdp_data(&rsdp, ACPI_BUILD_APPNAME6, ACPI_RSDP_REV_2,
> -                   NULL, &xsdt);
> -    build_rsdp(tables->rsdp, tables->linker, &rsdp);
> +    {
> +       AcpiRsdpData rsdp = {
> +           .revision = 2,
> +           .oem_id = ACPI_BUILD_APPNAME6,
> +           .xsdt_tbl_offset = &xsdt,
> +           .rsdt_tbl_offset = NULL,
> +       };
> +       build_rsdp(tables->rsdp, tables->linker, &rsdp);
> +    }
2 things here, imo:

- This is not more concise.
- It's code duplication as almost the same snippet is going to be used
  for i386/acpi-build.c

Cheers,
Samuel.