Hi Flash

On Thu, Aug 18, 2011 at 4:10 PM, Flash K bootloader99@yahoo.com wrote:

Thanks Graeme, Okay, so that means that U boot is a combination of Primary and Secondary bootloaders, ie loading the MBR and then loading the Kernel image.

U-Boot (like coreboot) sits at the lowest level - It starts executing from the 'Reset Vector' when the CPU is powered-up or reset

So is U Boot along the lines of Syslinux, Lilo, GRUB etc. I mean does it work in conjunction with a  BIOS?  I thought that U Boot was a combination of BIOS + Bootloaders. But thanks for clearing the doubt.

BIOS is a (somewhat standard) set of low-level functions which are accessed via software interrupts. Linux does not need BIOS (well, technically it still does for ACPI and possibly some PCI stuff) because it's drivers are written to control the hardware directly, so to run the Linux kernel, U-Boot does not have to implement a complete BIOS. U-Boot implements a very basic set which Linux needs early on to detect memory - It is just enough to fool Linux into booting after U-Boot has loaded the kernel image into memory (typically from a Flash memory devices, but some boards also support SATA interfaces and various file systems)

Regards,

Graeme

Will check out Coreboot.

Regards, Flash

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From: Graeme Russ graeme.russ@gmail.com To: Flash K bootloader99@yahoo.com Cc: "u-boot@lists.denx.de" u-boot@lists.denx.de Sent: Wednesday, August 17, 2011 10:54:30 PM Subject: Re: [U-Boot] Support for Intel i7 2nd GEneration processors

Hi Flash,

On Thu, Aug 18, 2011 at 3:38 PM, Flash K bootloader99@yahoo.com wrote:

...

Hi,

I would like to know if U boot supports the Intel 2nd generation core i7 processors.

No it doesn't (at least not yet)

Be aware that U-Boot is a boot-loader for embedded devices (phones, routers, set-top boxes, TV's etc) and not a general purpose BIOS for a PC. You might want to have a look at coreboot (www.coreboot.org) if you are looking for a FOSS implementation of a PC BIOS - They may have i7 support.

Regards,

Graeme

Hi Flash,

Note: I have no experience with (U)EFI On Tue, Aug 30, 2011 at 3:35 PM, Flash K bootloader99@yahoo.com wrote:

Hi Graeme, I was checking out other alternatives to BIOS. I came across EFI , a new technology that seems to replace the BIOS in the near future. However I am still not clear as to where EFI fits in the booting process. They say that EFI cannot replace the BIOS but plans to do so in the near future.

(U)EFI cannot replace BIOS because most OS's still depend on BIOS to boot. BIOS provides a standard way for an OS to do some fundamental operations in real-mode (the mode the x86 CPU boots into) before the OS's switches to protected mode (and hence can no longer use BIOS). After the switch to protected mode, the OS's drivers interface directly to the hardware. Some of these fundamental operations include determining memory size and loading the core OS components from the hard drive

FAQs at http://www.uefi.org/about/ Intel also says that they are providing support for some motherboards. So is UEFI meant for use with the existing BIOS or with a custom developed BIOS from Uboot/Coreboot? Some information online also says that UEFI can be used as a payload for Coreboot. The entire thing is a little confusing. I am not able to understand where UEFI fits in with the BIOIS?

I suppose you could call (U)EFI a 'bootloader' of sorts. I theory, you could write an (U)EFI for a motherboard and have it do everything BIOS currently does (provided you knew all the ins-and-outs of the hardware components). I gather that (U)EFI is far more extensible than coreboot or U-Boot - But it is also a lot bigger (I have heard numbers up to 2MB - U-Boot is <256kB). I gather that the size is due to a single (U)EFI image being able to cater for multiple hardware configurations - Each U-Boot image is tailored to a very specific hardware configuration (or very limited set thereof)

As a coreboot payload, I think coreboot does some low-level init of the motherboard hardware (SDRAM for example) and then passes control onto (U)EFI

So until Linux and Windows support (U)EFI and stop supporting BIOS, (U)EFI is not going to replace BIOS

Regards,

Graeme