LinuxQuestions.org - What is bigphysarea used for?

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What is bigphysarea used for?

Hi there,

These days I'm trying to start up a new driver and I'm pretty sure that the driver memory allocation is 'colliding' with this thing called "bigphysarea". I've googled a lot to find out what it is all about, but I couldn't find any good description on what is the bigphysarea used for, and what are the consequences of not having one.
I've also red the file under /usr/src/linux/Documentation/bigphysarea.txt but it is only a description of the kernel functions for allocating more than 128kB physical memory...

If anyone can give me an idea of the purpose of bigphysarea or at least post a link to a document desribing it more detailed, I'll be very thankful.

After witnessing so huge an interest about this topic I found a small but clear description of the bigphysarea patch to the linux kernel:

Quote:

Bigphysarea allows you to reserve a large portion of contiguous physical memory at boot time which can be allocated/deallocated by kernel drivers.
This sort of hack is necessary for devices such as RAM-less video framegrabbers which need a big chunk of contiguous physical RAM,larger than whatever get_free_pages or kmalloc can provide. Also, this memory is safe to remap_page_range() into user space, e.g., for mmap().

Taken from http://www.polyware.nl/~middelink/En/hob-v4l.html.
:)