[syslinux] Using syslinux.efi while doing UEFI HTTP boot iso PXE boot

[Gregory Bartholomew]

On Fri, Dec 13, 2019 at 7:32 PM JZB <jzb at z2zcorp.com> wrote:

> On 2019-12-13 08:36, Gregory Lee Bartholomew via Syslinux wrote:
> > On Fri, 2019-12-13 at 08:47 +0100, jps--- via Syslinux wrote:
> >> Hi,
> >>
> >> We are currently testing PXE booting with syslinux.efi in UEFI mode.
> >> This is working fine.
> >> However the loading of syslinux.efi and the config files is still using
> >> TFTP protocol, the rest kernel and initrd is loaded using HTTP protocol.
> >> We would like to use only HTTP protocol.
> >> In UEFI it is possible to use HTTP boot instead off PXE boot.
> >> Questions:
> >> 1.   If we load syslinux.efi with HTTP will this work ?
> >> 2.   If we load syslinux.efi with HTTP, will syslinux then load it
> config
> >> files with HTTP or TFTP ?
> >> 3.   In UEFI 2.8 it is possible to provide the next server manually
> (not
> >> using DHCP).
> >>          Will syslinux work with HTTP boot and a manually provided next
> >> server (no DHCP data) ?
> >>
> >
> > I think iPXE supports downloading and chainloading UEFI binaries over
> HTTP. You
> > would probably want to compile a custom ipxe.efi binary with an embedded
> script
> > that downloads syslinux.efi and the config files before executing "chian
> > syslinux.efi".
> >
>
> iPXE would still be load via TFTP.  If the issue is to load even the NBP
> via HTTP, then the BIOS has to support it.  Most UEFI BIOSes do, but you
> have to enable it in BIOS.  Its typically next to the PXE BOOT settings,
> and you can choose IPv4, IPv6, HTTP, etc.  Older UEFI BIOSes may not
> support this...
>

iPXE doesn't have to be loaded via TFTP. It can be written to the network
card's programmable ROM (https://ipxe.org/howto/romburning) or saved on the
workstation's ESP. But yeah, if the UEFI firmware already supports it, then
that is the easiest way to go. Many network cards come from the
manufacturer with iPXE pre-loaded on their ROMs. Just turn on the BIOS POST
messages and watch closely when the computer starts to boot off of the NIC
-- you'll likely notice "iPXE version xxx" scroll by in the POST messages.