Re: [Qemu-devel] [PATCH v5 10/12] hw/mips: malta: Add KVM support

[Aurelien Jarno]

On Thu, Jun 19, 2014 at 12:34:24PM -0700, Sanjay Lal wrote:
> 
> On Jun 19, 2014, at 9:27 AM, Aurelien Jarno <address@hidden> wrote:
> 
> > On Tue, Jun 17, 2014 at 11:10:35PM +0100, James Hogan wrote:
> >> In KVM mode the bootrom is loaded and executed from the last 1MB of
> >> DRAM.
> > 
> > What is the reason for that? I am not opposed to that, but if it is
> > really needed, it means that loading a bootloader into the flash area
> > (for example YAMON) won't work and that this should be forbidden to the
> > user.
> > 
> 
> In trap and emulate mode, both the kernel and userland run in user mode on 
> the processor. Virtual addresses >= 0x80000000 are only accessible in kernel 
> mode, and the default flash area (VA: 0xbfc00000/PA: 0x1fc00000) falls in 
> this range.
> 
> We therefore decided to relocate the bootloader to the last 1MB of RAM.  This 
> area is excluded from the RAM ranges supplied to the kernel, so it should not 
> be accessible to the user.
> 

Thanks for the explanation. It means we should disable the support for
booting from the flash (using -pflash) in KVM mode, as it would simply
not work.

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
address@hidden                 http://www.aurel32.net