PALO, the HPPA boot loader, requires a partition of type F0 somewhere in the first 2GB. This is where the boot loader and an optional kernel and RAMdisk will be stored, so make it big enough for that — at least 4Mb (I like 8–16MB). An additional requirement of the firmware is that the Linux kernel must reside within the first 2GB of the disk. This is typically achieved by making the root ext2 partition fit entirely within the first 2GB of the disk. Alternatively you can create a small ext2 partition near the start of the disk and mount that on /boot, since that is the directory where the Linux kernel(s) will be stored. /boot needs to be big enough to hold whatever kernels (and backups) you might wish to load; 25–50MB is generally sufficient.