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Shutemov" , linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Denis Mukhin Subject: Re: [PATCH v1 0/6] x86/boot: Enable earlyprintk on MMIO (8-bit) Message-ID: References: <20250502123145.4066635-1-andriy.shevchenko@linux.intel.com> <3c1bd53c8ee5fe0a6e281551dfe2089679e8e5eb.camel@infradead.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3c1bd53c8ee5fe0a6e281551dfe2089679e8e5eb.camel@infradead.org> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo On Mon, May 05, 2025 at 07:35:04AM -0700, David Woodhouse wrote: > On Mon, 2025-05-05 at 17:05 +0300, Andy Shevchenko wrote: > > On Fri, May 02, 2025 at 10:33:49AM -0700, David Woodhouse wrote: > > > 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? > > > > Do you mean to add MMIO 8-bit to kexec assembly code and other parts like you > > did in the below mentioned change? > > > > I can try it at some point, but have no time right now for this. > > I would appreciate if you can give a try for this patch series > > functionality to see if it helps for the initial messages (as > > far as I understand you also want to have this in the second > > kernel, right?). > > I'll see if I can find the time to take a look. Got a branch I can pull > your series from? Yeo, https://bitbucket.org/andy-shev/linux/commits/branch/topic%2Fx86%2Fboot-earlyprintk. -- With Best Regards, Andy Shevchenko