[U-Boot] UBoot porting to cortex-m3 based SoC

Before starting the project I'd like to have some advices from the community about the feasibility of porting U-Boot/ucLinux to a cortex-m3 based SoC with limited resources (up to 512K flash, up to 64K SRAM). I limit my questions to U-Boot only and will post similar ones to ucLinux mailing-list. But it will be certainly appreciated if you can also share your experience and thoughts on ucLinux.

1. How much is supported in terms of Cortex-M3 in U-Boot?

2. Is it possible to port u-boot (including ucLinux) to a SoC with such limited resources? What's the minimum footprint of U-Boot across all the processors/architectures it supports?

3. What's the best toolchain to compile U-Boot for Cortex-M3?

Thanks a lot, -Shawn.