Re: [Linux-fbdev-devel] Re: Generic VESA framebuffer driver and Video card BOOT?
From: Pavel Machek <hidden>
Date: 2004-10-20 17:47:40
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Hi!
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BTW, does this look like right way to POST VGA BIOS from real mode? It is what we currently use... and it works on some machines... movw $0xb800, %ax movw %ax,%fs movw $0x0e00 + 'L', %fs:(0x10)What is this for?
Debugging.
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cli cld # setup data segment movw %cs, %ax movw %ax, %ds # Make ds:0 point to wakeup_start movw %ax, %ss mov $(wakeup_stack - wakeup_code), %sp # Private stack is needed for ASUS board movw $0x0e00 + 'S', %fs:(0x12)We have never needed to set up a private stack. What ASUS board was it that you had problems with and needed to do this for?
This is running at system resume, so it is not normal boot. Some ASUS Athlon 900MHz machine needed this; I'm no longer using this one.
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pushl $0 # Kill any dangerous flags popfl movl real_magic - wakeup_code, %eax cmpl $0x12345678, %eax jne bogus_real_magic testl $1, video_flags - wakeup_code jz 1f lcall $0xc000,$3The call to 0xC000:0x0003 is the entry point to POST the card. However for PCI cards you need to make sure that AX is loaded with the bus, slot and function for the card that is being POST'ed. It will pass this value to the PCI BIOS Int 0x1A functions in order to find itself, so if this is not set many BIOS'es will not work.
Ok, this one is bad... ... In case of just one vga adapter, we should be able to store its parameters in some well-known place. For more than one adapter, we'll definitely need to run BIOS in emulator. Pavel -- People were complaining that M$ turns users into beta-testers... ...jr ghea gurz vagb qrirybcref, naq gurl frrz gb yvxr vg gung jnl!