make PHYS_OFFSET determined at run time (unfinished)

[jassisinghbrar@gmail.com (jassi brar)]

On Wed, Jan 20, 2010 at 11:39 PM, Steve Chen <schen@mvista.com> wrote:
> On Wed, 2010-01-20 at 02:32 +0000, Ben Dooks wrote:
>> On Tue, Jan 19, 2010 at 08:21:52PM -0600, Steve Chen wrote:
>> > On Wed, 2010-01-20 at 00:55 +0000, Ben Dooks wrote:
>> > > On Wed, Jan 20, 2010 at 09:26:41AM +1300, Ryan Mallon wrote:
>> > > > Uwe Kleine-K?nig wrote:
>> > > > > Hello,
>> > > > >
>> > > > > I'm looking into making PHYS_OFFSET determined at run time. ?I saw a
>> > > > > patch for it that already made it a few times on the list[1].
>> > > > >
>> > > > > I'm not yet done, but first want to announce that I look into that to
>> > > > > prevent duplicate work---so if you intended to do the same let's look
>> > > > > together---and to post some clean up patches that are the result up to
>> > > > > now of my digging in the boot code.
>> > > > >
>> > > > > I will send now three patches in reply to this mail, and later hopefully
>> > > > > more.
>> > > > >
>> > > > > Best regards
>> > > > > Uwe
>> > > > >
>> > > > > [1] e.g. http://thread.gmane.org/gmane.linux.ports.arm.kernel/53793/
>> > > > >
>> > > >
>> > > > One of the problems that got brought up previously was the 'make uImage'
>> > > > can end up generating unbootable images with runtime PHYS_OFFSET. The
>> > > > older format uImage's (pre 1.3.3) encode a load address (zrealaddr), so
>> > > > uImage's need to have a fixed load address encoded.
>> > > >
>> > > > As I stated in the previous thread, this is _not_ a kernel issue,
>> > > > however it is no good having a kernel which contains support for two
>> > > > boards which boot from different address and then generating a uImage
>> > > > which can only boot on one of them without warning the user about this
>> > > > problem. Otherwise you are going to start getting "I did make uImage and
>> > > > my board won't boot" problems.
>> > > >
>> > > > There are a few solutions to this problem:
>> > > > 1) Drop uImage make support and require users generate them manually.
>> > > > 2) Have a uImage offset config option to allow uImage users to specify
>> > > > what they want the load address to be. See:
>> > > > http://thread.gmane.org/gmane.linux.ports.arm.kernel/53151/focus=53230
>> > > > 3) Print an error if "make uImage" is run for a kernel which has more
>> > > > than one boot address (possible?)
>> > > > 4) Use FIT U-Boot images. This is supported from U-Boot 1.3.3 onwards,
>> > > > however a number of people are still using older U-Boots.
>> > >
>> > > Or of course, boot zImages. I belive u-boot has support for zImage.
>> >
>> > Is there a clean way to pass kernel parameters and machine type from
>> > u-boot to zImage? ?Last time I boot zImage in u-boot, some ugly hack was
>> > needed in ARM startup code. ?Just wondering if there is a better way.
>>
>> u-boot should be doing the right thing, I thought uImage was simply a
>> zImage wrapped in the right uboot descriptors to tell uboot it was a
>> kernel and where to load it.
>>
>> Certianly uboots i've used can boto zImage just fine.
>
> I'm also able to boot zImage under u-boot. ?However, I had to set r1
> manually, and I don't know how to pass kernel parameters (stuff passed
> into kernel uImage via bootargs) to zImage. ?Any tips will be greatly
> appreciated.
Perhaps you use 'go' instead of 'bootm' command in u-boot?
How about:-

 u-boot # <load zImage@_addr_ by some means>

 u-boot # setenv machid <your machine ID in hex without the '0x'>
 u-boot # saveenv //persistently save the machid
             // now you don't need to set machid even after cold reset

 u-boot # bootm _addr_

hth.