[syslinux] DEFAULT versus UI

Gene Cumm gene.cumm at gmail.com
Mon Sep 13 06:02:36 PDT 2010


On Thu, Sep 9, 2010 at 14:44, H. Peter Anvin <hpa at zytor.com> wrote:
> On 08/28/2010 04:32 AM, Gene Cumm wrote:
>> I'm posting this as I'm trying to evaluate DEFAULT versus UI.
>>
>> As it stands right now, the use of the UI directive means that DEFAULT
>> is effectively ignored from the command line.  If you specify UI and
>> DEFAULT and use (vesa)menu.c32, (vesa)menu.c32 will use DEFAULT unless
>> a MENU DEFAULT option exist in the current context.  If the attempt to
>> execute a command fails, returning you to the "boot: " prompt, hitting
>> enter will return you to the menu (assuming you haven't switched
>> configs).  If your specified UI does not exist, hitting enter will
>> again attempt to load the UI (probably unsuccessfully unless it's
>> PXELINUX and you encountered an error that won't repeat on a
>> particular retry).
>>
>> If you've specified UI and DEFAULT but the UI file can not be found or
>> otherwise loaded from media completely, I think it would be more
>> advantageous to the user to return an error stating (probably in
>> addition to the existing output) "UI could not be loaded" and then
>> hitting enter at "boot: " would activate DEFAULT rather than failing
>> again on UI.  Alternatively, it could again attempt to load UI but on
>> failure, run DEFAULT.  However, if loading UI was successful, hitting
>> enter from the "boot: " prompt should return to the menu.
>>
>> Thoughts/comments?
>>
>> HPA, I'm interested in working on this if there's interest.
>>
>
> Sounds reasonable to me.
>
>        -hpa

I've got step one on this done.  If UI fails with a file not found,
use DEFAULT as the auto_boot entry (tweaking DefaultLevel).  Next is
to then attempt auto_boot again with the new DefaultLevel.  I also
need to look into other error conditions (not COM32R, for example) and
possibly a few more minor things.

-- 
-Gene




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