[U-Boot] [PATCH] common/dlmalloc: support reinit bin for fast reset

[Wolfgang Denk]

Dear Macpaul Lin,

In message <AANLkTimK=c1+aVsJcRwtPG4hPKp6Lvvu0Ji6a_7B3O_u at mail.gmail.com> you wrote:
> 
> User could evaluate the board function with evb_board, then develops the product
> software by using u-boot and Linux kernel to simulate the real product behavior.
> Once the user has done development process, he/she can replace the evb_loader
> with real generic u-boot (with CONFIG_SKIP_LOWLEVEL_INIT is disabled).
>
> That's why we may need "warm start" or "warm boot" which let user
> restart the u-boot
> without resetting the board and jumping to the evb_loader again..

All understood, except for the "That's why" - IO do not see any part
in your explanation above why the "reset" in U-Boot should not perform
a real reset operation?

[Of course I wonder which features your evb_loader provides that are
missing in U-Boot and cannot be added there, but that's your decision.]

> Even there exist a need with "warm boot", the NDS32 architecture still do
> CPU and memory reset. In the current reset_cpu() function whihc NDS32
> has provided
> (it could be hooked to watchdog reset or warm boot), reset still do
> the following reset
> process.

Why?  All this is bogus if you perform a real hardware reset as you
are supposed to do.

> > If you want to extend the U-Boot design by adding support for a
> > restart feature (or "warm start"), then this needs to be done right;
> > setting of a few selected variables is definitely not sufficient.
>
> Okay, if I want to make U-boot supports "restart feature", it seems I need to
> find a reasonable method to reload the data segment and clear bss. It seems
> the most secure method is to load code (data segment) from flash.

...or form another copy of the data segment.

> Do you have further idea of supporting feature "restart" (warm start)?

Well, I can just say that I see no need for such a fature - doing a
real reset is much more reliable and convenient, as you do not need
any extra code.

Best regards,

Wolfgang Denk

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