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Re: multiboot information structure flags are confusing me


From: Timmy Douglas
Subject: Re: multiboot information structure flags are confusing me
Date: Wed, 13 Feb 2002 20:01:07 -0600 (CST)

Alex Thiel <address@hidden> said:
>On Tuesday 12 February 2002 04:02, Timmy Douglas wrote:
>> i want to enable some flags for the multiboot information
>> structure. so i can get some VBE info.
>>
>> however, the docs talk about two separate groups of flags: the ones in
>> the binary header and the multiboot info flags. it says that the
>> multiboot info pointer is passed in %ebx (or whatever) to the main
>> function, but how can i set the flags so grub can put what i want in
>> the structure?
>>
>
>There are indeed two sets of flags: the OS requests features via the header 
>in the OS image (see chapter OS image format in the multiboot documentation), 
>and GRUB passes information about the actual state of the system in the 
>multiboot info structure.

ok thanks

>For example, the OS requests VBE information via bit 2 of the flags field in 
>the OS header. Suppose the BIOS did not support VBE, then GRUB would set the 
>corresponding flag in the multiboot info structure to zero and leave it to 
>the application to handle the situation.

and one thing about your docs:


             +-------------------+
     0       | vbe_control_info  |
     4       | vbe_mode_info     |
     8       | vbe_mode          |
     10      | vbe_interface_seg |
     12      | vbe_interface_off |
     14      | vbe_interface_len |
             +-------------------+

i assume that vbe_interface_len is 2 bytes?



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