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From: "Martyn Welch" <martyn.welch@radstone.co.uk>
To: "Asgard" <dubalom@gmail.com>, <linux-kernel@vger.kernel.org>
Subject: RE: alloc_bootmem - Kernel panic
Date: Wed, 7 Feb 2007 16:47:20 -0000	[thread overview]
Message-ID: <F38DEABE0E171746B133C1ABBD142D9706325502@radmail.Radstone.Local> (raw)

Hi Asgard,

Thank you for your reply.
	
> I don't sure, that linux performs to allocate bootmem after kernel already booted.
> As I know, bootmem allocator "destroyed" when kernel initializes buddy allocator.
> Indeed you can look at arch/i385/mm/init.c, mem_init routine.
> kernel passes all bootmem pages to buddy system, so bootmem allocator can't be used after it. 
	
That explains why I can't use alloc_bootmem. It'd assumed that do_initcalls and hence functions labelled with module_init() were called early enough, mainly because LDD3 suggests using alloc_bootmem. It seems the vt driver uses console_init() instead, which is called much earlier.

Which leads me to the question: what is the best method to reserve a large (~4MB) coherent buffer for DMA transfers?

Is there any way of using alloc_bootmem from a driver (compiled into the kernel) without delving further into kernel code?

Martyn

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             reply	other threads:[~2007-02-07 16:47 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-07 16:47 Martyn Welch [this message]
2007-02-07 18:24 ` Asgard
  -- strict thread matches above, loose matches on Subject: below --
2007-02-07 13:41 Martyn Welch

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