Le 11/02/2011 11:51, Aneesh V a écrit : > Hi Albert, > > On Wednesday 09 February 2011 02:20 AM, Albert ARIBAUD wrote: >> Le 08/02/2011 21:18, stefano babic a écrit : >>> Am 08.02.2011 20:26, schrieb Magnus Lilja: >>>> Patch reposted as a separate mail a couple of minutes ago. >>>> >>>> As I mention in the patch I think Fabio's patch has to be applied >>>> first. >>> >>> I think your patch is ok - Fabio fixed the syntax error as you do. We >>> need only one of them. >>> >>>> Another solution would be to change my patch somewhat to apply it first >>>> and then update Fabios patch to only touch the i.MX31-PDK specific >>>> files. >>> >>> IMHO this is the preferred way, because the two issues are orthogonal. >>> Your patch fixes booting from NAND for ARM11, and Fabio's patch fix the >>> mx31pdk board only. >> >> Agreed. >> >> Note also that there was a recent patch to ARM926's start.S (replacing >> 'adr r1, _start' with 'ldr r1, _TEXT_BASE' at line 284). The same should >> be done on arm1136. > > Is this going to happen for armv7 too? What is the real reason behind > this proposal. What is the case when _start is not same as _TEXT_BASE(I > looked at the archives but couldn't filter out the original discussion > on this)
The difference is that _TEXT_BASE always contains the link-time address of _start, whereas references to _start may contain a different value if the code is executed somewhere else than at the link-time address. /Normally/, u-boot should always execute first at the link-time address -- that's a base constraint. /But/ this change makes it more resilient to out-of-link-time-address execution, and I want, at some time in the future, to find a way for u-boot to be able to start anywhere -- within reasonable limits: anywhere in NOR for a NOR-based U-boot, anywhere in RAM for a RAM-based U-boot, but I am not talking about a generic, run-in-RAM-or-NOR-or-anywhere, binary. Yet. :) > I see a problem with that. _TEXT_BASE is based on > CONFIG_SYS_TEXT_BASE. In our SPL's case CONFIG_SYS_TEXT_BASE indicates > the TEXT_BASE for u-boot and *CONFIG_SYS_SPL_TEXT_BASE* indicates the > TEXT_BASE for SPL. Both are defined and useful in SPL because one is > used for linking SPL while the other is used while loading u-boot from > MMC. So, CONFIG_SYS_TEXT_BASE used in the start.S of SPL will not be > correct. The change I indicate is under the #else of a #ifdef CONFIG_NAND_SPL, so it will not apply to SPL. Does that still cause an issue with armv7? > In the worst case we need to define yet another label in the linker > scripts like __text_base. But I was wondering if we could maintain the > status quo for armv7: that is 'adr r1, _start' As long as you run the u-boot start code at the link-time address, there will be no difference except the code is more correct with respect to what it should do; and if you run it elsewhere, which you should not, you have slightly better chances that it manages to survive. > Best regards, > Aneesh Amicalement, -- Albert. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
