Re: [Qemu-devel] [PATCH v7 3/3] i386: populate floppy drive information in DSDT

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Jan 26, 2016 at 02:50:25PM +0100, Igor Mammedov wrote:
> From: Roman Kagan <rkagan@virtuozzo.com>
> 
> On x86-based systems Linux determines the presence
> and the type of floppy drives via a query of a CMOS field.
> So does SeaBIOS when populating the return data for
> int 0x13 function 0x08.
> 
> However Windows doesn't do it. Instead, it requests
> this information from BIOS via int 0x13/0x08 or through
> ACPI objects _FDE (Floppy Drive Enumerate) and _FDI
> (Floppy Drive Information) of the floppy controller object.
> On UEFI systems only ACPI-based detection is supported.
> 
> QEMU doesn't provide those objects in its ACPI tables
> and as a result floppy drives aren't invisible

are invisible

> to Windows
> on UEFI/OVMF.
> 
> This patch adds those objects to the floppy controller
> in DSDT, populating them with the information from
> respective QEMU objects.
> 
> Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> ---
> fixup:
>   - rebase on latest FDC refactoring
> ---
>  hw/i386/acpi-build.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 58 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index 2f685fb..1d291d8 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -38,6 +38,7 @@
>  #include "hw/acpi/bios-linker-loader.h"
>  #include "hw/loader.h"
>  #include "hw/isa/isa.h"
> +#include "hw/block/fdc.h"
>  #include "hw/acpi/memory_hotplug.h"
>  #include "hw/mem/nvdimm.h"
>  #include "sysemu/tpm.h"
> @@ -1227,10 +1228,47 @@ static void build_hpet_aml(Aml *table)
>      aml_append(table, scope);
>  }
>  
> -static Aml *build_fdc_device_aml(void)
> +static Aml *build_fdinfo_aml(int idx, uint8_t type, uint8_t cylinders,
> +                             uint8_t heads, uint8_t sectors)

acpi spec says these are WORD values. Are they really uint8_t?

> +{
> +    Aml *dev, *fdi;
> +
> +    dev = aml_device("FLP%c", 'A' + idx);
> +
> +    aml_append(dev, aml_name_decl("_ADR", aml_int(idx)));
> +
> +    fdi = aml_package(0x10);

Why 0x10 and not 16?

> +    aml_append(fdi, aml_int(idx));  /* Drive Number */
> +    aml_append(fdi,
> +        aml_int(cmos_get_fd_drive_type(type)));  /* Device Type */
> +    aml_append(fdi,
> +        aml_int(cylinders - 1));  /* Maximum Cylinder Number */
> +    aml_append(fdi, aml_int(sectors));  /* Maximum Sector Number */
> +    aml_append(fdi, aml_int(heads - 1));  /* Maximum Head Number */

Doesn't above change on media change?
If so this must be created dynamically, not hard-coded at machine
done type.

> +    /* SeaBIOS returns the below values for int 0x13 func 0x08 regardless of
> +     * the drive type, so shall we */

    /*
     * Format comments
     * Like this please
     */

    /* Not
     * Like this */


> +    aml_append(fdi, aml_int(0xAF));  /* disk_specify_1 */
> +    aml_append(fdi, aml_int(0x02));  /* disk_specify_2 */
> +    aml_append(fdi, aml_int(0x25));  /* disk_motor_wait */
> +    aml_append(fdi, aml_int(0x02));  /* disk_sector_siz */
> +    aml_append(fdi, aml_int(0x12));  /* disk_eot */
> +    aml_append(fdi, aml_int(0x1B));  /* disk_rw_gap */
> +    aml_append(fdi, aml_int(0xFF));  /* disk_dtl */
> +    aml_append(fdi, aml_int(0x6C));  /* disk_formt_gap */
> +    aml_append(fdi, aml_int(0xF6));  /* disk_fill */
> +    aml_append(fdi, aml_int(0x0F));  /* disk_head_sttl */
> +    aml_append(fdi, aml_int(0x08));  /* disk_motor_strt */
> +
> +    aml_append(dev, aml_name_decl("_FDI", fdi));
> +    return dev;
> +}
> +
> +static Aml *build_fdc_device_aml(ISADevice *fdc)
>  {
> +    int i;
>      Aml *dev;
>      Aml *crs;
> +    uint32_t fde_buf[5] = {0, 0, 0, 0, cpu_to_le32(0x2)};

Pls document values.

>  
>      dev = aml_device("FDC0");
>      aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0700")));
> @@ -1243,6 +1281,21 @@ static Aml *build_fdc_device_aml(void)
>          aml_dma(AML_COMPATIBILITY, AML_NOTBUSMASTER, AML_TRANSFER8, 2));
>      aml_append(dev, aml_name_decl("_CRS", crs));
>  
> +    for (i = 0; i < MAX_FD; i++) {
> +        uint8_t type = isa_fdc_get_drive_type(fdc, i);
> +
> +        if (type < FLOPPY_DRIVE_TYPE_NONE) {
> +            uint8_t cylinders, heads, sectors;
> +
> +            fde_buf[i] = cpu_to_le32(0x1);

Pls document values.

> +            isa_fdc_get_drive_geometry(fdc, i, &cylinders, &heads, &sectors);
> +            aml_append(dev,
> +                build_fdinfo_aml(i, type, cylinders, heads, sectors));
> +        }
> +    }
> +    aml_append(dev, aml_name_decl("_FDE",
> +               aml_buffer(sizeof(fde_buf), (uint8_t *) fde_buf)));

No space after cast please.

> +
>      return dev;
>  }
>  
> @@ -1387,13 +1440,15 @@ static Aml *build_com_device_aml(uint8_t uid)
>  
>  static void build_isa_devices_aml(Aml *table)
>  {
> +    ISADevice *fdc = pc_find_fdc0();
> +
>      Aml *scope = aml_scope("_SB.PCI0.ISA");
>  
>      aml_append(scope, build_rtc_device_aml());
>      aml_append(scope, build_kbd_device_aml());
>      aml_append(scope, build_mouse_device_aml());
> -    if (!!pc_find_fdc0()) {
> -        aml_append(scope, build_fdc_device_aml());
> +    if (!!fdc) {
> +        aml_append(scope, build_fdc_device_aml(fdc));
>      }
>      aml_append(scope, build_lpt_device_aml());
>      aml_append(scope, build_com_device_aml(1));
> -- 
> 1.8.3.1