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Message-ID: <010101c1cfd3$8a87cfd0$1a02a8c0@allyourbase>
From: "Dan Maas" <dmaas@dcine.com>
To: "chiranjeevi vaka" <cvaka_kernel@yahoo.com>
Cc: <linux-kernel@vger.kernel.org>
In-Reply-To: <fa.l19uvvv.1hjmo8t@ifi.uio.no>
Subject: Re: using kmalloc
Date: Wed, 20 Mar 2002 00:53:20 -0500
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> I am getting some problems with kmalloc. If I tried to
> allocate more than certain memory then the system is
> hanging while booting with the changed kernel. Can you
> suggest me how to come out this situation. Can't I
> allocate as much I want when I want to allocate in the
> kernel.

kmalloc() allocates physically-contiguous pages of memory. Due to
fragmentation, more than 64KB-128KB of contiguous pages might not be
available, and hence kmalloc() will fail.

To allocate more memory, use vmalloc(), which allocates and maps physically
disjoint pages into a virtually-contiguous region. Be careful when doing DMA
to a vmalloc() area, since it is not physically contiguous and exists only
in the kernel's virtual memory map... Also I believe vmalloc()ed memory is
only accessible from (the context of) the process in which it was allocated
(?).

Regards,
Dan

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