Re: how big an image downloaded and booted by gPXE could be?

Hi,
As gPXE doesn't run in long mode it can only address 4GB of RAM(that's
the maximum for 32 bit).
You could however boot a 64 bit linux kernel, and let the initrd fetch
the rootfs to a 4GB ramdisk.
How you can accomplish this is probably specific to the distribution you use.

There is also a 64 bit version of gPXE for EFI booted systems. EFI
isn't supported widely yet, so I don't know if you can use it. I'm
also unsure whether this version of gPXE allows larger images or has
the same limits.

Thomas

On Wed, Dec 9, 2009 at 5:28 PM, Luca <[email protected]> wrote:
> Hi all,
>  I have a system with 8G of RAM. When I try to download and boot with gPXE
> an image whose size is around 4G, gPXE gets stuck after downloading it. Is
> there any limitation with gPXE on how big the downloaded image could be?
> Thanks.
>
> Here is a more detailed description of what I'm trying to do.
> I have two identical systems (each with 8G of RAM).
> I installed Fedora 11 on one of this. I made a copy of the HD (let's call it
> rootfs.img) and created a initial ramdisk containing this rootfs.img. This
> init file in initial ramdisk at a certain point switch root, mounting
> rootfs.img. The size of this ramdisk is 4G (let's call it ramdisk.img).
>
> I wanted to use gPXE to download the kernel and ramdisk.img and boot it.
>
> So I have gPXE downloading the following gPXE script
> #!gpxe
>
> kernel https://192.168.1.189/vmlinuz root=/dev/ram0 init=linuxrc
> ramdisk_size=4000000 ramdisk_blocksize=1024
> initrd https://192.168.1.189/ramdisk.img
> boot
>
> gPXE downloads the script and the the kernel and the initrd, but then it
> gets stuck (don't think the kernel is started by gPXE, don't even see the
> message "Probing EDD ... or anything else). Only message I see, is the one
> telling me gPXE is done downloading both kernel and ramdisk.img.
>
> Thanks,
>  Luca
>
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