On 18/06/2019 13:28, Andrii Anisov wrote:
+xen-devel
Please don't cross-post e-mail. If you move the thread to xen-devel, then
xen-users should be droppped.
Hello Julien,
I am a bit confused. Linux is able to bring-up CPU in hyp mode with the current
U-boot. Why would we need more changes for Xen?
TI's ROM code starts all CPUs in NS PL1, doesn't matter if it is boot or
secondary core.
If you look at Linux code [1], you'll see, that after the secondary core
bringup Linux does switch that core from NS PL1 to PL2 (hyp mode) using ROM
code interface (smc 0).
At some moment XEN dropped all to-hyp-mode switching code. So I did switch
secondaries to hyp mode in u-boot with the loop which replicates the ROM Code
logic in terms of waiting for an event and checking aux registers.
Switch to hyp-mode is fairly complex and depends on your processor. Hence why it
was dropped in both Linux and Xen.
However, calling an SMC would be acceptable to me. Stefano, any opinion?
[1]
https://elixir.bootlin.com/linux/v5.1/source/arch/arm/mach-omap2/omap-headsmp.S#L62
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Julien Grall
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