[U-Boot] [PATCH] omap3evm: Pass 'mem' argument to linux kernel

[Premi, Sanjeev]

> -----Original Message-----
> From: Igor Grinberg [mailto:grinberg at compulab.co.il] 
> Sent: Tuesday, September 27, 2011 5:35 PM
> To: Premi, Sanjeev
> Cc: u-boot at lists.denx.de
> Subject: Re: [U-Boot] [PATCH] omap3evm: Pass 'mem' argument 
> to linux kernel

Sorry missed this mail earlier...

> 
> On 09/27/11 14:21, Sanjeev Premi wrote:
> > In absence of this argument, Linux kernel doesn't boot.
> > 
> > Default value has been set to 128M to ensure that
> > Linux kernel boots on older EVMs as well.
> 
> This change affects all EVMs, unless they explicitly change/remove
> the memsize variable or change the *args variables.

Today without this patch, all EVMs should anyway be broken :(
...but may be working as users may have their own bootargs with
"mem=XYZM" in their bootargs.

The patch only ensures that the kernel would boot if there was
no "saved" environment e.g. when environment partition is erased.
or when u-boot is flashed on new boards.

> 
> Can't the get_ram_size() function be used for detecting the actual
> amount of RAM? and then the memory tag or FDT equivalent
> (if there is one) used to pass the memory size information?
> 

Yes something like this can be done, but that would mean string
manipulation at run-time. Question is - when we should/ shouldn't
do this manipulation.

If user wants to explicitly pass only a portion of memory to Linux
using environment variables, we shouldn't be manipulating the
bootargs.

~sanjeev

[snip]...[snip]