Re: [Bochs-developers] UEFI and jump_protected: gate type 0unsupported

[Sebastian H. <he...@gm...>]

Sebastian Herbszt wrote:
> Stanislav Shwartsman wrote:
>> Looks like it is somehow related to memory issue (I mean it is not enough to
>> change BIOSROMSZ to enable 2M BIOS).
>> LGDT reads from address 0xfff80 which returns 0xffffffff 0xffffffff -> looks
>> like bogus memory.
>> I guess it supposed to be something else.
>> Need to look into memory.cc/misc_mem.cc and see why it goes to bogus.
>> 
>> Stanislav
> 
> The BIOS mapping could be the problem. The high mapping at 0xffe00000
> seems correct because we can execute the code. The data is used from 0xf0000.
> So if the mapping is bogus wrong data will be accessed.
> gdtr at 0xffffff80 looks ok and points to 0xffffff90. gdtr at 0x000fff80 is all 0xf.

If i modify readPhysicalPage()
to use
    *data_ptr = BX_MEM_THIS rom[BIOSROMSZ - 0x100000 + (a20addr & BIOS_MASK)];
instead of
    *data_ptr = BX_MEM_THIS rom[a20addr & BIOS_MASK];

i can make it return the first two correct bytes, but the second memory read is still wrong.
First one seems to use read_virtual_word_32() which somehow ends up in readPhysicalPage()
and the second one is read_virtual_dword_32() which doesn't end up there. The memory handling
in Bochs looks like a maze to me, so i might give up sooner or later.  Hope you can figure it out.

Sebastian