Re: [PATCH v1 0/6] x86/boot: Enable earlyprintk on MMIO (8-bit)

[David Woodhouse]

On Fri, 2025-05-02 at 15:29 +0300, Andy Shevchenko wrote:
> Some of the platforms may have no legacy COM ports and only provide
> an MMIO accessible UART. Add support for such to earlyprintk for the
> boot phase of the kernel.

Shiny. I had to hack QEMU's PCI serial port to do unnatural things, in
order to test the mmio32 variant which was the only thing the
earlyprintk code used to support. But I *did* so, and it works with the
kexec debugging.

Can you add support for this mode to the kexec debugging too, please?

I believe it's currently in tip/asm. This should be a simple example to
work from:
https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?h=x86/asm&id=7516e7216bdfb9e2fab0a0ca3bd23cb2e61e46ed

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