Re: [U-Boot] [PATCH v1 2/2] WIP: x86: acpi: Generate SPCR table

On Tue, Sep 25, 2018 at 10:27:33AM +0800, Bin Meng wrote:

On Sat, Sep 22, 2018 at 9:05 PM Andy Shevchenko andriy.shevchenko@linux.intel.com wrote:

...

+/* SPCR (Serial Port Console Redirection table) */ +struct __packed acpi_spcr {

•   struct acpi_table_header header;        /* Common ACPI table header */
  

•   u8 interface_type;      /* 0=full 16550, 1=subset of 16550 */
  

•   u8 reserved[3];
  

•   struct acpi_gen_regaddr serial_port;    /* The base address of the Serial Port register set */
  

•   u8 interrupt_type;
  

•   u8 pc_interrupt;
  

•   u32 interrupt;          /* Global system interrupt */
  

•   u8 baud_rate;
  

•   u8 parity;
  

•   u8 stop_bits;
  

•   u8 flow_control;
  

•   u8 terminal_type;
  

•   u8 reserved1;
  

•   u16 pci_device_id;      /* Must be 0xffff if not PCI device */
  

•   u16 pci_vendor_id;      /* Must be 0xffff if not PCI device */
  

•   u8 pci_bus;
  

•   u8 pci_device;
  

•   u8 pci_function;
  

•   u32 pci_flags;
  

•   u8 pci_segment;
  

•   u32 reserved2;
  

+};

I see not every member of 'struct __packed acpi_spcr' is populated. Are they not used by kernel? If kernel does not use it, it is used by Windows?

No idea about Windows, but there are two statements: - *not all* should be filled, otherwise it would be contradictory (PCI vs. non-PCI device, for example) - Linux doesn't use all of them, indeed