Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol forrelocatable bzImage

From: H. Peter Anvin
Date: Wed May 09 2007 - 01:08:54 EST


H. Peter Anvin wrote:
> yhlu wrote:
>> On 5/8/07, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:
>>> Since the whole point is to detect the case where we don't have
>>> a screen at all it makes sense to check several additional variables
>>> and make certain that they are all 0. Agreed?
>> need one good way to find if there is support vga console.
>
> There really isn't one, at least not given the current data structure;
> the data structure has an "isVGA" flag, but if that is 0 it's supposed
> to mean CGA/MDA/HGC/EGA, as opposed to VGA...

Of course, one could argue that since all of those were obsolete by the
time Linux was first created, that it probably doesn't matter and that
isVGA == 0 pretty much means the more obvious thing.

MDA/HGC stuck around for quite a while for debugging, since it was
non-conflicting with VGA, but even if it is, the reason people put it in
their system is to have something that the OS doesn't readily see.

-hpa
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