Re: [PATCH] Loading windows in macbook

[Bean]

On Wed, Jun 25, 2008 at 6:19 PM, Marco Gerards <address@hidden> wrote:
> Bean <address@hidden> writes:
>
>> On Wed, Jun 25, 2008 at 4:38 AM, Javier Martín <address@hidden> wrote:
>>> El mié, 25-06-2008 a las 04:11 +0800, Bean escribió:
>>>> 2. Macbook will halt if we disable a20, so I add a new option
>>>> --keep-a20 to keep the a20 gate open.
>>> Does any OS fail to boot if it has A20 enabled when it is jumped to?
>>> AFAIK some BIOS even had an option to enable it at POST time, so I think
>>> we should make this new option the default and have an option called
>>> "--reset-a20" or something like that.
>>
>> I don't know of any os that would fail if a20 is enabled. Normally,
>> they try to enable it as soon as possible as they need to access upper
>> memory. So making it default is not a bad idea.
>
> It's disabled for legacy reasons.  Some old DOS applications expect
> addresses to wrap around.  And thus a20 gate should be disabled.

Right, but new version of dos will enable a20 as well, so application
that depend on such feature would have serious compatibility issue.
Anyway, the question is whether we should leave it on by default. A20
is a common issue for buggy bios, I think we should leave it alone as
much as possible.

-- 
Bean