> -----Original Message----- > From: linuxppc-embedded-bounces+sstrublic=hypercom.com at ozlabs.org > [mailto:linuxppc-embedded-bounces+sstrublic=hypercom.com at ozlabs.org] On > Behalf Of David Hawkins > Sent: Friday, March 03, 2006 1:07 PM > To: Rune Torgersen > Cc: linuxppc-embedded at ozlabs.org > Subject: Re: Linux on PPC > > > >>Right, thats I made sure to say; Physical Memory Map. > >> > >>For example, on the Artesyn manual on their PrPMC they give a > >>physical memory map, and in the Yosemite board, there is a > >>physical memory map. I know many of the memory areas can be > >>redefined in hardware to have a different memory location, but > >>its still a physical address. > >> > > > > Still not right. Even the physical memory is software settable. What > > matters is what chip-select things are hooked up to, and then map those > > chip selects correctly (size, base address, access with and so on) > > Hi Rune, > > Thanks for responding. > > Thats what I meant with 'redefined in hardware'. But yes, redefined > up to the limit of the wiring on the board of course (chip-selects > and bus widths). That's where having the board schematic is > invaluable. > > But ok, I'm pretty sure I get the point, and hopefully the > original poster understands a bit more too. > > Given a board that you expect to run Linux on, I would imagine > you would select hardware settings consistent with making > Linux happy, i.e., defining 'in software' (the bootloader) > the physical address map (eg. like the Embedded Planet reference > manual for the 440EP Yosemite board), and then setup U-Boot and > Linux to program the TLBs to translate to those same addresses. > > When looking at the Yosemite board, I booted U-Boot and compared > device dcr settings to the recommended ones in the EP manual. Then > when I booted Linux, I took a look and found that on the whole, Linux > didn't touch too much of the things setup by U-Boot, i.e., the > responsibility for setting up the Linux environment was mainly > the job of the bootloader. > > So, if I had a board with a custom bootloader, I would be > concerned that the bootloader might not know enough about > Linux, to setup the hardware correctly.
The boot loader should, ideally, NOT know anything about Linux except for knowing that since a Linux is being loaded, it requires some information at boot time, and the format in which to provide said information. Steve > > Does that sound right? > > Dave > > > > > > _______________________________________________ > Linuxppc-embedded mailing list > Linuxppc-embedded at ozlabs.org > https://ozlabs.org/mailman/listinfo/linuxppc-embedded
