updated ipxe configuration

docs/pxe-boot.md

@@ -7,7 +7,9 @@ The `pxe-boot` host serves HTTP boot assets for iPXE clients.
 - Hostname: `pxe-boot`
 - Web service: nginx on TCP port 80
 - PXE root: `/srv/pxe`
-- Generated iPXE menu: `/srv/pxe/boot/menu.ipxe`
+- iPXE entry script: `/srv/pxe/boot.ipxe`
+- Generated iPXE menu: `/srv/pxe/menu.ipxe`
+- TFTP fallback script: `/srv/pxe/boot/autoexec.ipxe`
 - Boot binaries copied from the Nix `ipxe` package:
   - `/srv/pxe/boot/ipxe.efi`
   - `/srv/pxe/boot/undionly.kpxe`
@@ -24,6 +26,18 @@ The host creates these directories with systemd tmpfiles:
 /srv/pxe/rescue
 ```
 
+The HTTP iPXE chain is:
+
+```text
+undionly.kpxe or ipxe.efi
+  -> autoexec.ipxe from the TFTP root, when iPXE requests it
+  -> http://192.168.2.247/boot.ipxe
+  -> http://192.168.2.247/menu.ipxe
+```
+
+The same scripts are also exposed under `/boot/` for compatibility with older
+checks and any DHCP option that already points there.
+
 The generated menu currently exposes entries for:
 
 - NixOS installer
@@ -46,7 +60,15 @@ nix eval .#nixosConfigurations.pxe-boot.config.system.build.toplevel.drvPath --r
 After deployment by an operator, basic service checks are:
 
 ```bash
+curl http://pxe-boot/boot.ipxe
+curl http://pxe-boot/menu.ipxe
 curl http://pxe-boot/boot/menu.ipxe
+curl http://pxe-boot/boot/autoexec.ipxe
 curl -I http://pxe-boot/boot/ipxe.efi
 curl -I http://pxe-boot/boot/undionly.kpxe
 ```
+
+During a successful BIOS chainload, TFTP should deliver `undionly.kpxe` once,
+then nginx should log requests for `/boot.ipxe` and `/menu.ipxe`. Repeated TFTP
+downloads of `undionly.kpxe` indicate the iPXE stage is still not reaching the
+HTTP chain.