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Re: [PATCH] Fix alignment of early reservation for EBDA

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From: Ingo Molnar <mingo@...>
To: Alexander van Heukelum <heukelum@...>
Cc: Andi Kleen <ak@...>, Thomas Gleixner <tglx@...>, LKML <linux-kernel@...>, Alexander van Heukelum <heukelum@...>
Subject: Re: [PATCH] Fix alignment of early reservation for EBDA
Date: Sunday, February 24, 2008 - 3:41 pm

* Alexander van Heukelum <heukelum@mailshack.com> wrote:


well, that's what your EBDA descriptor says - it's set to 9fc00 which is 
512 bytes below the VGA range. This behavior didnt really change over 
v2.6.24 (which reserved 'into' the VGA range too), it's just that in 
v2.6.25 we also print out these early reservations. Can you see any 
regression? There should be no harm from overlapping into the VGA range 
- these "reservations" only make RAM unavailable for normal allocations.

your patch on the other hand rounds the EBDA area down which could in 
theory be unsafe on other boxes (where there could be real RAM above the 
EBDA area): the safest approach is to round the beginning of it down, 
the end of it up (to page boundary). Your patch _should_ be OK, but in 
practice it doesnt hurt to reserve a bit more around the edges than to 
accidentally give a page to the OS that the BIOS might rely upon.

	Ingo
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Messages in current thread:
[PATCH] Fix alignment of early reservation for EBDA, Alexander van Heukelum, (Sun Feb 24, 1:46 pm)
Re: [PATCH] Fix alignment of early reservation for EBDA, H. Peter Anvin, (Sun Feb 24, 10:18 pm)
Re: [PATCH] Fix alignment of early reservation for EBDA, Alexander van Heukelum, (Mon Feb 25, 12:54 pm)
Re: [PATCH] Fix alignment of early reservation for EBDA, Andi Kleen, (Wed Feb 27, 10:25 am)
Re: [PATCH] Fix alignment of early reservation for EBDA, Ingo Molnar, (Mon Feb 25, 1:01 pm)
[PATCH] reserve_early end-of-conventional-memory to 1MB, Alexander van Heukelum, (Mon Feb 25, 2:07 pm)
Re: [PATCH] reserve_early end-of-conventional-memory to 1MB, H. Peter Anvin, (Mon Feb 25, 2:13 pm)
Re: [PATCH] reserve_early end-of-conventional-memory to 1MB, Alexander van Heukelum, (Mon Feb 25, 3:46 pm)
Re: [PATCH] reserve_early end-of-conventional-memory to 1MB, H. Peter Anvin, (Mon Feb 25, 5:17 pm)
Re: [PATCH] reserve_early end-of-conventional-memory to 1MB, Ingo Molnar, (Tue Feb 26, 5:30 am)
Re: [PATCH] reserve_early end-of-conventional-memory to 1MB ..., Andi Kleen, (Wed Feb 27, 10:38 am)
Re: [PATCH] reserve_early end-of-conventional-memory to 1MB ..., H. Peter Anvin, (Wed Feb 27, 12:44 pm)
Re: [PATCH] reserve_early end-of-conventional-memory to 1MB ..., Alexander van Heukelum, (Wed Feb 27, 4:01 pm)
Re: [PATCH] reserve_early end-of-conventional-memory to 1MB, Andi Kleen, (Wed Feb 27, 10:26 am)
[PATCH] reserve end-of-conventional-memory to 1MB on 32-bit, Alexander van Heukelum, (Thu Feb 28, 9:13 am)
[RFC] use realmode code to reserve end-of-conventional-memor..., Alexander van Heukelum, (Thu Feb 28, 9:28 am)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., Ian Campbell, (Thu Feb 28, 5:12 pm)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., H. Peter Anvin, (Thu Feb 28, 5:14 pm)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., Ian Campbell, (Thu Feb 28, 7:16 pm)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., Jeremy Fitzhardinge, (Tue Mar 4, 1:44 pm)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., Eduardo Habkost, (Wed Mar 5, 11:59 am)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., Jeremy Fitzhardinge, (Wed Mar 5, 12:38 pm)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., H. Peter Anvin, (Wed Mar 5, 1:27 pm)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., H. Peter Anvin, (Wed Mar 5, 12:08 pm)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., Eduardo Habkost, (Wed Mar 5, 12:53 pm)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., H. Peter Anvin, (Wed Mar 5, 1:28 pm)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., Jeremy Fitzhardinge, (Wed Mar 5, 1:28 pm)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., H. Peter Anvin, (Wed Mar 5, 1:38 pm)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., Ingo Molnar, (Fri Feb 29, 4:00 pm)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., Mark McLoughlin, (Tue Mar 4, 7:41 am)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., Ingo Molnar, (Tue Mar 4, 10:33 am)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., Jeremy Fitzhardinge, (Tue Mar 4, 11:13 am)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., Ingo Molnar, (Tue Mar 4, 11:25 am)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., Jeremy Fitzhardinge, (Tue Mar 4, 12:02 pm)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., Ingo Molnar, (Tue Mar 4, 12:15 pm)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., Mark McLoughlin, (Tue Mar 4, 12:15 pm)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., Ingo Molnar, (Tue Mar 4, 12:23 pm)
Re: [RFC] use realmode code to reserve end-of-conventional-m..., Ian Campbell, (Tue Mar 4, 11:12 am)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-..., Ian Campbell, (Thu Feb 28, 5:09 pm)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-..., Alexander van Heukelum, (Fri Feb 29, 7:49 am)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-..., Mark McLoughlin, (Fri Feb 29, 1:14 pm)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-..., Alexander van Heukelum, (Fri Feb 29, 2:38 pm)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-..., H. Peter Anvin, (Fri Feb 29, 2:44 pm)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-..., Alexander van Heukelum, (Fri Feb 29, 2:56 pm)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-..., Mark McLoughlin, (Fri Feb 29, 6:06 pm)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-..., Alexander van Heukelum, (Sat Mar 1, 12:09 pm)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 64-..., Alexander van Heukelum, (Sat Mar 1, 12:12 pm)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-..., Mark McLoughlin, (Tue Mar 4, 7:44 am)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-..., Jeremy Fitzhardinge, (Tue Mar 4, 11:18 am)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-..., Alexander van Heukelum, (Tue Mar 4, 12:51 pm)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-..., Jeremy Fitzhardinge, (Tue Mar 4, 1:11 pm)
Re: [PATCH] reserve end-of-conventional-memory to 1MB, 32-bi..., Alexander van Heukelum, (Tue Mar 4, 2:57 pm)
Re: [PATCH] reserve end-of-conventional-memory to 1MB, 64-bi..., Alexander van Heukelum, (Tue Mar 4, 3:12 pm)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-..., H. Peter Anvin, (Tue Mar 4, 1:05 pm)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-..., Ingo Molnar, (Tue Mar 4, 10:49 am)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-..., Mark McLoughlin, (Tue Mar 4, 11:16 am)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-..., Ingo Molnar, (Tue Mar 4, 11:24 am)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-..., Alexander van Heukelum, (Tue Mar 4, 9:31 am)
Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-..., Alexander van Heukelum, (Fri Feb 29, 6:26 pm)
Re: [PATCH] Fix alignment of early reservation for EBDA, Andi Kleen, (Sun Feb 24, 3:27 pm)
Re: [PATCH] Fix alignment of early reservation for EBDA, Ingo Molnar, (Sun Feb 24, 3:41 pm)
Re: [PATCH] Fix alignment of early reservation for EBDA, Alexander van Heukelum, (Sun Feb 24, 4:53 pm)