[gPXE] [Etherboot-discuss] how big an image downloaded and booted by gPXE could be?

[Luca]

Thank you. So gPXE can address 4GB of RAM.

Then, if I gPXE boot with the following script

#!gpxe

  kernel https://192.168.1.189/vmlinuz root=/dev/ram0 init=linuxrc
  initrd https://192.168.1.189/ramdisk.img
  boot

the ramdisk's size could not exceed 2G (considering gPXE has to download it
and then load it in memory)?

Thank you,
  Luca

On Wed, Dec 9, 2009 at 9:09 AM, Thomas Miletich
<thomas.miletich at gmail.com>wrote:

> 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 <lucarx76 at gmail.com> 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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