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Re: [Qemu-discuss] How do i tell QEMU that memory i've have mapped is co

From: Peter Maydell
Subject: Re: [Qemu-discuss] How do i tell QEMU that memory i've have mapped is code?
Date: Mon, 12 Jan 2015 23:48:02 +0000

On 12 January 2015 at 23:18, Peter Fillmore <address@hidden> wrote:
> The setup code is <edited for brevity>:
>         MemoryRegion *sysmem = get_system_memory();
>         MemoryRegion *iap = g_new(MemoryRegion, 1);                           
>           //create pointer for region
>         memory_region_init_ram(iap, NULL, "vivotech.iap", 
> 0x1000,&error_abort); //init 0x1000 bytes of ram
>         vmstate_register_ram_global(iap);                                     
>                                   //register with qemu
>         memory_region_add_subregion(sysmem, 0x7FFFFFF0, iap);                 
>   //add to the sysmem

I'm confused; this doesn't look wrong, but it also doesn't seem
to have anything at all to do with the code fragment you quoted
in your previous email as being how you set up the memory.

Also is it really 0x1000 bytes starting at 0x7ffffff0 ?? That
sounds very weird -- usually memory is at some aligned address.
In fact I think this is the problem: we require the whole page
of the address space to be RAM to be able to execute out of it.
We can't deal with executing from pages which are split between
RAM and something else like the setup you have here. (Reading
or writing from that sort of mixed-usage page is fine; it's just
executing code that won't work.)

-- PMM

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