Unable to access FPGA device with virtual address returned by ioremap()

Valdis.Kletnieks at vt.edu Valdis.Kletnieks at vt.edu
Wed Dec 25 20:28:02 EST 2013

On Wed, 25 Dec 2013 16:00:41 -0800, Sri Ram Vemulpali said:

> Second, when I typed command in bash "free -m" it shows 756MB memory
> available. I used "mem=" commandline option to tell kernel to use 4GB
> memory. But after booting the kernel it still shows 756MB. Why is this?

If it's showing 756M because you have 768M of physical ram (3 x 256M),
using mem=4G won't do what you think.  That parameter is to *reduce* the
amount of memory the kernel will use - it's usually useful on a machine that
has (say) 16G, but you want to restrict the kernel to 10G and leave the other
6G for custom hardware or something.
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