Re: GRUB VBE Mode Info

[Andrei Borzenkov]

В Sat, 16 May 2015 22:17:04 +1000
Malhar Palkar <address@hidden> пишет:

> To the help desk,
> 
> I am currently developing a hobby OS, of which I am planning to use GRUB 2
> as the bootloader. Instead of having to reinvent the wheel and use the
> horrid protected mode VBE interface, I have am instead passing my preferred
> mode (132 x 60 EGA text) to GRUB via the multiboot header.

Do you mean *from* GRUB to OS kernel? If not, how exactly do you pass
information to GRUB? You need to have some other bootloader then?

>                                                           However, there
> is no way of the OS knowing whether the mode was implemented or not, or if
> it was, which is the relevant video memory. The multiboot specification
> says "The fields ‘vbe_control_info’ and ‘vbe_mode_info’ contain the
> physical addresses of vbe control information returned by the vbe Function
> 00h and vbe mode information returned by the vbe Function 01h,
> respectively."
> My question: Is the mode information described above relevant to the video
> mode set by GRUB?
> 

Yes. GRUB fills in relevant information in multiboot header when it can
set video mode. So if OS sees it it can assume mode was set by
bootloader. 

> I apologise if I have misread or misunderstood the specification. I look
> forward to receiving a reply.
> 
> Thanks a million!