FWIW, I've been trying DSLinux on a M3 Real with Sakura 1.42, and a M3 Perfect Lite for the extra RAM.
Under Sakura, DSLinux will not boot if launched with A (results in white screens). It must be started with X, Y, or a long tap with the stylus. Dragging the entry to the left, as if to open the options screen, also launches it.
DSLinux will only register 16MB of RAM when booted under Sakura. It can be checked using the "free" command. This bothers me a lot, since the M3 Lite cart has 32MB.
Under Touchpod, booting DSLinux via the Card menu (the third icon) shows two options: boot homebrew from Slot-1 or from Slot-2. Both of them work, but if you choose Slot-2, "free" will report 16MB of RAM, like Sakura; whereas if you choose Slot-1, "free" will report the right amount, 32MB.
Is there a way to choose between Slot-1 and Slot-2 when launching homebrew from within Sakura, as there is in Touchpod?