Wind River Pulsar is an alternative to PetaLinux for our Zynq SoMs, and as we go forward it is our intent to continue to enhance the user experience to make it the go-to platform for embedded application development. PetaLinux still has a place as an easy-to-use memory-resident kernel and root file system, but Pulsar uses a non-volatile RFS allowing for a much larger set of packages that provide considerable flexibility in customizing the environment for production and development. It also has the advantage of the optional security shield, providing long term support and upgrades to incorporate enhancements and provide protection against unwanted intrusions.
As with any Linux system, PL logic is accessed via the standard (or custom) drivers provided with the PL IP. On an ARM-based system that lacks a BIOS, you must inform the OS of the location and characteristics of new hardware through the device tree. And depending on the IP and it's inclusion in the mainline version on which Pulsar is based, you may also need to update the kernel configuration and rebuild the kernel using the free wr-core tools available from Wind River OpenSourceLabs. Kernel drivers are accessed programatically via ioctl, read and write, and sysfs drivers can be accessed directly from user space (even command line) by manipulating entries under the /sys folder.
The normal flow for this product is to begin with a certfied image that boots from uSD card, and do your application development in one of three methods: 1) on target, 2) using the Wind River Helix Application Cloud or 3) using a host cross-compiler with the Wind River OpenSourceLabs tools. The HAC includes a full visual debugger for application code, which seamlessly integrates with your connected board. You should also be able to use the Xilinx SDK to connect a debug session using the Ethernet cable, but I haven't tried that.
I don't believe there is any technical reason why you couldn't download the kernel over JTAG, but it is not a flow we have experimented with.
