Single binary kernel for all i.MX

[Gadiyar, Anand]

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

- Anand