[SeaBIOS] [PATCH] mark VBE mapping as reserved in e820
Carl-Daniel Hailfinger
c-d.hailfinger.devel.2006 at gmx.net
Sun Jan 24 15:26:55 CET 2010
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
--
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"We are juggling too many chainsaws and flaming arrows and tigers."
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