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Re: [Xen-devel] Using mini-os ioremap()

To: Matthew Fioravante <matthew.fioravante@xxxxxxxxxx>
Subject: Re: [Xen-devel] Using mini-os ioremap()
From: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>
Date: Wed, 5 Jan 2011 23:55:52 +0100
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Matthew Fioravante, le Wed 05 Jan 2011 14:24:55 -0500, a écrit :
>  I'm trying to map some mmio pages into my mini-os domain to use a 
> hardware device. The device is at address fed40000. I'm calling 
> ioremap() on this address but its failing, telling me that mfn fed40 is 
> in ram space. (Its failing the mfn_is_ram() check.)
> What am I doing wrong here?

Mmm, I don't think anything you're doing is wrong. Notice the comment:

static long system_ram_end_mfn;
int mfn_is_ram(unsigned long mfn)
    /* very crude check if a given MFN is memory or not. Probably should
     * make this a little more sophisticated ;) */
    return (mfn <= system_ram_end_mfn) ? 1 : 0;

Do you have more than 4GiB memory, i.e. 0xfed40000 is actually between
two RAM areas?  In such case mfn_is_ram has to really get more

(In the interim you could just comment the mfn_is_ram() test from
do_ioremap to make things work)


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