RE: Booting Linux from an ACE File
-Original Message- From: [EMAIL PROTECTED] [mailto:linuxppc-embedded- [EMAIL PROTECTED] On Behalf Of mojtaba Sent: Friday, May 16, 2008 4:58 AM To: linuxppc-embedded@ozlabs.org Subject: Booting Linux from an ACE File Dear all, Could you please explain what happens exactly when Linux is booting from a compact flash? The systemAce file is essentially a script of JTAG commands, some of which target the FPGA with configuration data and some target the PowerPC/microblaze with memory write commands. To my few knowledge, the Linux compressed image will be copied somewhere in memory, will be uncompressed and the control will jump to the beginning address of the Linux kernel. Is there any boot loader that copies the Linux compressed image to the memory? Essentially SystemAce does this for you and jumps to the Linux bootwrapper code which begins decompressing the kernel. Where in memory does it put the Linux kernel? For example, if I have 2 DDRs in my hardware, in which of them it will be put the kernel? The kernel is compiled at a particular address, typically targetting whatever memory is low in the system. I believe the default target address is 0x4. So whatever DDR memory lives at this address will be targetted. Can I set the kernel location in memory manually? If you change how the bootwrapper code and linker script work, yes. Might be an stupid question but: Is it possible for the kernel to be half in BRAMS and half in DDR? There have been some recent patches on the microblaze mailing lists that attempt to put some of the latency-critical code (exception handlers and the like) in BRAM. Doing this is likely pretty architecture specific, since you probably have a particular goal in mind. Steve This email and any attachments are intended for the sole use of the named recipient(s) and contain(s) confidential information that may be proprietary, privileged or copyrighted under applicable law. If you are not the intended recipient, do not read, copy, or forward this email message or any attachments. Delete this email message and any attachments immediately. ___ Linuxppc-embedded mailing list Linuxppc-embedded@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-embedded
Booting Linux from an ACE File
Dear all, Could you please explain what happens exactly when Linux is booting from a compact flash? To my few knowledge, the Linux compressed image will be copied somewhere in memory, will be uncompressed and the control will jump to the beginning address of the Linux kernel. Is there any boot loader that copies the Linux compressed image to the memory? Where in memory does it put the Linux kernel? For example, if I have 2 DDRs in my hardware, in which of them it will be put the kernel? Can I set the kernel location in memory manually? Might be an stupid question but: Is it possible for the kernel to be half in BRAMS and half in DDR? Regards, Moji ___ Linuxppc-embedded mailing list Linuxppc-embedded@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-embedded
Re: Booting Linux from an ACE File
mojtaba ha scritto: Dear all, Could you please explain what happens exactly when Linux is booting from a compact flash? To my few knowledge, the Linux compressed image will be copied somewhere in memory, will be uncompressed and the control will jump to the beginning address of the Linux kernel. Is there any boot loader that copies the Linux compressed image to the memory? Where in memory does it put the Linux kernel? For example, if I have 2 DDRs in my hardware, in which of them it will be put the kernel? Can I set the kernel location in memory manually? Might be an stupid question but: Is it possible for the kernel to be half in BRAMS and half in DDR? Regards, Moji ___ Linuxppc-embedded mailing list Linuxppc-embedded@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-embedded Is there any boot loader that copies the Linux compressed image to the memory? Yes there are several boot-loader for example U-Boot. Where in memory does it put the Linux kernel? For example, if I have 2 DDRs in my hardware, in which of them it will be put the kernel? The kernel usually is copied at the start of the memory, so if you have mapped the address 0x in the first bank, here will be copied it. Can I set the kernel location in memory manually? Yes but usually it's not needed and you have to be carefully to modify it. ___ Linuxppc-embedded mailing list Linuxppc-embedded@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-embedded
Re: Booting Linux from an ACE File
On Fri, May 16, 2008 at 5:57 AM, mojtaba [EMAIL PROTECTED] wrote: Dear all, Could you please explain what happens exactly when Linux is booting from a compact flash? To my few knowledge, the Linux compressed image will be copied somewhere in memory, will be uncompressed and the control will jump to the beginning address of the Linux kernel. There are several methods to do this. Option 1 is to pass the kernel zImage.elf to genace so that it gets wrapped up into the ace file itself and is loaded into RAM by the SystemACE on FPGA initialization. However, this requires that your FPGA design gets RAM initialized before the SysACE starts squirting in the Linux image (which isn't always the case). This option is also slow. Option 2 is to use an small bootloader blob (I think Xilinx has a technote with something suitable) loaded into BRAM that reads the CF card and copies a Linux image (hint; build a simpleImage when using arch/powerpc) off the CF and into RAM. This method boots the system faster, but requires a little bit more work. Cheers, g. -- Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd. ___ Linuxppc-embedded mailing list Linuxppc-embedded@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-embedded
