Re: [SeaBIOS] [PATCH] mark VBE mapping as reserved in e820

[Carl-Daniel Hailfinger]

Hi Izik,

On 24.01.2010 00:35, Izik Eidus wrote:
> To make life easier for us we can look on the acpi spec (3b) that say:
>
> 14.5 Example Address Map
> This sample address map (for an Intel processor-based system) describes a machine that has 128 MB of
> RAM, 640 KB of base memory and 127 MB of extended memory. The base memory has 639 KB available
> for the user and 1 KB for an extended BIOS data area. A 4-MB Linear Frame Buffer (LFB) is based at 12
> MB. The memory hole created by the chip set is from 8 MB to 16 MB. Memory-mapped APIC devices are
> in the system. The I/O Unit is at FEC00000 and the Local Unit is at FEE00000. The system BIOS is
> remapped to 1 GB–64 KB.

The sentence above is a bug in the spec. The system BIOS is remapped to
4 GB - 64 kB (not 1 GB - 64 kB).
> The 639-KB endpoint of the first memory range is also the base memory size reported in the BIOS data
> segment at 40:13. The following table shows the memory map of a typical system.
>                                     Table 14-8 Sample Memory Map
>   Base (Hex)      Length     Type                      Description
>   0000 0000       639 KB     AddressRangeMemory        Available Base memory. Typically the same value
>                                                        as is returned using the INT 12 function.
>                            Hewlett-Packard/Intel/Microsoft/Phoenix/Toshiba
>                                                   System Address Map Interfaces 399
> Base (Hex) Length Type                 Description
> 0009 FC00  1 KB   AddressRangeReserved Memory reserved for use by the BIOS(s). This
>                                        area typically includes the Extended BIOS data
>                                        area.
> 000F 0000  64 KB  AddressRangeReserved System BIOS
> 0010 0000  7 MB   AddressRangeMemory   Extended memory, which is not limited to the
>                                        64-MB address range.
> 0080 0000  4 MB   AddressRangeReserved Chip set memory hole required to support the
>                                        LFB mapping at 12 MB.
> 0100 0000  120 MB AddressRangeMemory   Baseboard RAM relocated above a chip set
>                                        memory hole.
> FEC0 0000  4 KB   AddressRangeReserved I/O APIC memory mapped I/O at FEC00000.
> FEE0 0000  4 KB   AddressRangeReserved Local APIC memory mapped I/O at FEE00000.
> FFFF 0000  64 KB  AddressRangeReserved Remapped System BIOS at end of address space.
>
> So we can see that even the acpi spec example mark the LFB region as reserved.

No, the memory hole is marked as reserved. The LFB region is not listed
above.

Regards,
Carl-Daniel