Single binary kernel for all i.MX
u.kleine-koenig at pengutronix.de
Fri Nov 12 13:50:57 EST 2010
On Fri, Nov 12, 2010 at 10:59:33PM +0530, Gadiyar, Anand wrote:
> 2010/11/12 Uwe Kleine-König <u.kleine-koenig at pengutronix.de>:
> > Hi Shawn,
> > On Fri, Nov 12, 2010 at 11:40:41PM +0800, Shawn Guo wrote:
> >> I'm studying at the implementation. Can you please help me understand
> >> how "addruart" in plat-mxc/include/mach/debug-macro.S works for single
> >> image?
> >> .macro addruart, rp, rv
> >> ldr \rp, =UART_PADDR @ physical
> >> ldr \rv, =UART_VADDR @ virtual
> >> .endm
> >> We have this macro to get physical base address of UART. However
> >> UART_PADDR is defined as MX?_UART1_BASE_ADDR depending on
> >> CONFIG_ARCH_MX*. When all CONFIG_ARCH_MX* get defined in single image
> >> case, how does UART_PADDR work for all CONFIG_ARCH_MX*?
> > In a kernel that supports more than one SoC, DEBUG_LL won't work. This
> > is generally OK, because DEBUG_LL is only needed when bringing up a
> > machine. Therefor you can use a tailored kernel that only supports your
> > shiny new machine.
> > Uwe
> Hi Uwe,
> OMAP does have this working. For example, we can boot a single kernel image
> on OMAP2, OMAP3 and OMAP4 today, and we have DEBUG_LL working for
> sure on the last two - probably also on OMAP2.
> I'm not exactly sure how this mechanism works, but for every new machine we
> add, we usually add an entry in arch/arm/plat-omap/include/plat/uncompress.h
You're mixing things up, mach/uncompress.h is for the Uncompressing
Linux message when booting a zImage, mach/debug-macro.S is for DEBUG_LL
and used to get debug messages out of the serial interface (usually).
The former will work for a multi-soc-imx-image, the latter probably not.
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