[SOLVED] please help me to know details of boot.h source code

abdullah bin khaled · 09-18-2018, 10:44 PM

/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
#ifndef _ASM_X86_BOOT_H
#define _ASM_X86_BOOT_H

/* Internal svga startup constants */
#define NORMAL_VGA 0xffff /* 80x25 mode */
#define EXTENDED_VGA 0xfffe /* 80x50 mode */
#define ASK_VGA 0xfffd /* ask for it at bootup */

#endif /* _ASM_X86_BOOT_H */

i want to know are those macros are special purposed and different from general one . Where can i find detail of them and what does those octal number means?

berndbausch · 09-18-2018, 11:33 PM

Strictly speaking, there are no macros. Macros are pieces of code, often parameterized. The defines in this file provide names for numbers. Besides, those numbers are hexadecimal, not octal.

Of course the purpose of these defines is special. They determine graphics modes at boot time. This is documented at https://www.kernel.org/doc/Documentation/svga.txt. By the way, I found this page with this Google search:

Code:

site:kernel.org ask_vga

I don’t know what you mean by “general one”.

syg00 · 09-18-2018, 11:47 PM

The OP has opened 3 threads on the same theme, and not answered any of them.

berndbausch · 09-19-2018, 12:18 AM

Quote:

Originally Posted by syg00

The OP has opened 3 threads on the same theme, and not answered any of them.

Not quite true; he updated the other question I answered (Sep 15) when he realized that the original wording was not adequate. Still, I wonder why somebody must crawl around in the deep bowels of Linux, seemingly without knowing much about this rather complex subject.