On Wed, 2003-03-19 at 20:05, jwalden at digitalatlantic.com wrote: > > Thanks for the info - > > It doesn't look to me like the 4xx has a BAT - > what would I use instead? >
One way would be to use a locked TLB. I'm sure there are others. > Jerry Walden > > -----Original Message----- > From: Gary D. Thomas [mailto:gary.thomas at mind.be] > Sent: Wednesday, March 19, 2003 4:19 PM > To: Jerry Walden > Cc: linuxppc embedded > Subject: RE: CONFIG_SERIAL_TEXT_DEBUG causes exception > > > On Wed, 2003-03-19 at 14:04, Jerry Walden wrote: > > What other embedded board (hopefully a ppc) would you suggest - > > I don't see any special provisions in the kernel for a custom > > mapping of these registers based on a configuration option for any > > specific board - this appears to be generic code that meant for > > all platforms - I believe what you say regarding what I have to > > do: > > > > 1) I can't find sample code that you refer to. > > 2) I am confused as to why this code is in the kernel in the way it is > > because it seems to me that most embedded processors have an MMU, > > so why the comment in that section of code that says "assuming the > > firmware setup the board properly...." > > > > As soon as the kernel starts, there are *no* mappings, other than > RAM, unless explicitly set up. > > Try looking at arch/ppc/platforms/pumaA.c (in the 2_4_devel kernel). > This explicit mapping happens in the "platform_init" function, > near the end. > > n.b. it's polite to copy such dialogue to the mailing list so that > everyone else can benefit. If you want (or need) private help, you > can arrange for it. > > > Thanks Much for Your Help > > > > Jerry Walden > > > > -----Original Message----- > > From: owner-linuxppc-embedded at lists.linuxppc.org > > [mailto:owner-linuxppc-embedded at lists.linuxppc.org]On Behalf Of Gary D. > > Thomas > > Sent: Wednesday, March 19, 2003 12:54 PM > > To: jwalden at digitalatlantic.com > > Cc: linuxppc embedded > > Subject: Re: CONFIG_SERIAL_TEXT_DEBUG causes exception > > > > > > > > On Wed, 2003-03-19 at 10:47, Jerry Walden wrote: > > > > > > Hello: > > > > > > I have a custom PPC405GPr board that I have successfully ported u-boot to. > > > > > > I am now at the stage of trying to bring Linux up on the board. > > > > > > I have CONFIG_SERIAL_TEXT_DEBUG defined for the kernel that I am trying to > > > bring up. I would like to have this option so I can trace through the > > > kernel. > > > The comments in ppc4xx_setup.c in the function serial_putc indicate that > > as > > > long > > > as the firmware (in my case u-boot) has been initialized properly, then > > this > > > function > > > should work. I have verified the addresses that the function is trying to > > > write to > > > and they are correct. However, when serial_putc calls the first readb, I > > > get an > > > exception. > > > > > > Can someone please provide some pointers as to what might be wrong? > > > > You need to make sure that the serial registers are mapped at > > that point. I don't know the details of your U-boot implementation, > > but the kernel will most certainly not have this region mapped > > unless you make it happen explicitly. Look at some other embedded > > boards and you'll find code to set this up, typically using a BAT or > > some other special mapping. > > > > -- > > .--------------------------------------------------------. > > | Mind: Embedded Linux and eCos Development | > > |--------------------------------------------------------| > > | Gary Thomas email: gary.thomas at mind.be | > > | Mind ( http://mind.be ) tel: +1 (970) 229-1963 | > > | gpg: http://www.chez-thomas.org/gary/gpg_key.asc | > > '--------------------------------------------------------' > > > > > > > -- > --------------------------------------------------------. > | Mind: Embedded Linux and eCos Development | > |--------------------------------------------------------| > | Gary Thomas email: gary.thomas at mind.be | > | Mind ( http://mind.be ) tel: +1 (970) 229-1963 | > | gpg: http://www.chez-thomas.org/gary/gpg_key.asc | > '--------------------------------------------------------' > -- .--------------------------------------------------------. | Mind: Embedded Linux and eCos Development | |--------------------------------------------------------| | Gary Thomas email: gary.thomas at mind.be | | Mind ( http://mind.be ) tel: +1 (970) 229-1963 | | gpg: http://www.chez-thomas.org/gary/gpg_key.asc | '--------------------------------------------------------' ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
