Hi!

Thanks for you answer! I have found that one, but I need to be able to specify exactly what memory range that shall be protected. I did find the CONFIG_PRAM-parameter but I did not figure out how to tell u-boot exactly what range not to whipe-out. Such as do not destroy 0x1000-0x2000. Also the solution that I would like to find/create is to have the possibility to set a protect area using a system parameter in order to be able to change the protection zone without recompilation. Would that be a good feature?

Thanks, Markus

-----Original Message----- From: wd@denx.de [mailto:wd@denx.de] Sent: den 23 augusti 2007 12:42 To: Markus Malmgren Cc: u-boot-users@lists.sourceforge.net Subject: Re: [U-Boot-Users] Protect an area in RAM

In message DC6F86A94046A64094043D44A3A708F7A148D4@sestoex02.enea.se you wrote:

Many hardware manufactures provide their development platform with u-boot. I was wondering if there is a feature (did not find anything)

in

u-boot to protect a specific area in the RAM from being overwritten

when

u-boot boots a microcontroller? The reason for this is that we store debug information between restarts from our software and using u-boot this is destroyed.

I'm seriously surprised that you did not find anything. Did you actually search for "protected RAM"?

-> grep -ir 'protected ram' * README:- Protected RAM: README: "protected RAM", i. e. RAM which is not overwritten README: ... eventually: pRAM (Protected RAM - unchanged by reset) board/netstal/hcu5/README.txt: * - protected RAM include/configs/CCM.h:#define CONFIG_PRAM 512 /* reserve 512kB "protected RAM"*/ include/configs/CMS700.h:#undef CONFIG_PRAM /* no "protected RAM" */ include/configs/DP405.h:#define CONFIG_PRAM 2 /* reserve 2 kB "protected RAM" */ include/configs/PCI405.h:#define CONFIG_PRAM 2048 /* reserve 2 MB "protected RAM" */ include/configs/PN62.h:#define CONFIG_PRAM 1024 /* reserve 1 MB protected RAM*/ include/configs/VOM405.h:#undef CONFIG_PRAM /* no "protected RAM" */ include/configs/pcu_e.h:#define CONFIG_PRAM 2048 /* reserve 2 MB "protected RAM" */ lib_m68k/board.c: * - protected RAM lib_m68k/board.c: * reserve protected RAM lib_m68k/board.c: debug ("Reserving %ldk for protected RAM at %08lx\n", reg, addr); lib_m68k/board.c: * taking into account the protected RAM at top of memory lib_ppc/board.c: * - protected RAM lib_ppc/board.c: * reserve protected RAM lib_ppc/board.c: debug ("Reserving %ldk for protected RAM at %08lx\n", reg, addr); lib_ppc/board.c: * taking into account the protected RAM at top of memory

If this feature does not exist, one general solution would be to add a system parameter in which areas that are not to be destroyed could be added as a default feature of u-boot. Would this be a feature that others need as well? If so I will start to investigate what could be done.

This feature has been available for a long, long time, as well as a log driver which is intended to pass for example U-Boot POST information to the OS (Linux), or to allow U-Boot to dump Linux' log buffer after a crash.

I guess you should refine your search methods.

Best regards,

Wolfgang Denk

Hi again,

The OS supports moving the log memory area so that is not a problem. The reason why it would be good to be able to protect a memory area, independent of where it is located, without recompilation is to simplify the use for customers that have a hardware that are delivered with u-boot and no knowledge about u-boot. It would be very simple for them to just add a system parameter in order to protect a part of the RAM. It could be in the end of RAM and work as CONFIG_PRAM does, but the goal would be to remove the need for recompilation.

It seems like this feature already exists in some way, I misinterpreted this yesterday when I looked at the readme and source. Is it like this? If I have a compilation of u-boot that does not define CONFIG_PRAM, is still possible to add the environment parameter 'pram' to add protection of the upper X KB?

Thanks, Markus

-----Original Message----- From: wd@denx.de [mailto:wd@denx.de] Sent: den 23 augusti 2007 21:22 To: Markus Malmgren Cc: u-boot-users@lists.sourceforge.net Subject: Re: [U-Boot-Users] Protect an area in RAM

In message DC6F86A94046A64094043D44A3A708F7A14AFA@sestoex02.enea.se you wrote:

Thanks for you answer! I have found that one, but I need to be able to specify exactly what memory range that shall be protected. I did find

The pRAM area is always at the very upper end of the RAM. If you want to pass it unchanged between U-Boot and an OS and back there are not many options.

the CONFIG_PRAM-parameter but I did not figure out how to tell u-boot exactly what range not to whipe-out. Such as do not destroy 0x1000-0x2000. Also the solution that I would like to find/create is

to

have the possibility to set a protect area using a system parameter in order to be able to change the protection zone without recompilation. Would that be a good feature?

I have never seen a need for this, and, given the things you have to keep in mind (memory resizing coee after reset, eventually ECC initialization, making sure that both U-Boot and the OS agree on exactly the same memory area, etc., I don;t see an easy way to do what you want, either.

Why do you have to use a specific memory range? It sounds as if this was a restriction that comes from the OS - how about fixing the problem there?

Best regards,

Wolfgang Denk