From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DF7162FE085 for ; Tue, 6 May 2025 03:19:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746501562; cv=none; b=JV/xRa6UHUo2N2DqjShtqWY52QYyYpXfWzFjYuQBupUQhbgiiwG8Aft6O9G55is51OYfvHGozuC+aKbhA2sCcSjv1sfJFDGwiChjKoZvrtTFYVKVBhBroVFQxXixbB/IPVrYzJ3lPSinuyudJxit+iTCuweUgnsUM5nIeTex4RA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746501562; c=relaxed/simple; bh=SxeEi1tAOcX2d70LYt+z+Ni8g/gFI9Pu/YnGg+QnZrw=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=XggsQBbBhRkI2IqGD433BZQG2Vve0UYBJl2AWLRHpNQrxoT6K8C2wYaIjHX1uBIRCsE8HwvmKh5yJkI98ef6sZ4L1QL08MjNBr5aUMRGe9oWmW+lXcimUoLRE3/6UEhuqnQnxzqTDz9xn8031/nWuvxvxXxQKniMyJ/LpYXSMq8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=desiato.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=PmCqRO+t; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=desiato.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="PmCqRO+t" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=MIME-Version:Content-Type:References: In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=ZeZmCG8Rp23jEiEukTixuUunYCEKGdOE3CORiFF/t1s=; b=PmCqRO+tDPtGvCgrJ2l9DRop3S 3I3TQCs/Txy5Qy+LwusjMfmh3mJCBGerUbhu/bLy61JI9AiSMTHv4svO+UDwo7x4VfOLdUUKIH3eG yP2K2zQu71ABCbLY/V74qz5mqkA6fMcELJEpIXM0T3cf+ddHHqoLnCaV8tx1XI2+HTnblBJadiYtX WRjm+D/Fcv8RY1gS8AT4MojtHqQ6RQkjX5vMtLYnYn0QbfF8Mc4VBT2oarzfs5FMko/KggIFzeF7O 9fleafT3/DqrW3zhpD1LUVJdmi8d6W2aupJw7JSuC29mAiQrGAMvsirv+623/ulSDNow75xL7MQO7 vfwZShjw==; Received: from [65.133.87.50] (helo=u09cd745991455d.ant.amazon.com) by desiato.infradead.org with esmtpsa (Exim 4.98.1 #2 (Red Hat Linux)) id 1uC8pu-0000000FalN-0pHA; Tue, 06 May 2025 03:19:15 +0000 Message-ID: <0f861de2000013ba89f2adc2f1237e1b4abe248b.camel@infradead.org> Subject: Re: [PATCH v1 0/6] x86/boot: Enable earlyprintk on MMIO (8-bit) From: David Woodhouse To: Andy Shevchenko Cc: Ashish Kalra , "Kirill A. Shutemov" , linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Denis Mukhin Date: Mon, 05 May 2025 20:19:09 -0700 In-Reply-To: <944ddefdc0ef3dc0f78c7957afa7f12e360a4392.camel@infradead.org> References: <20250502123145.4066635-1-andriy.shevchenko@linux.intel.com> <3c1bd53c8ee5fe0a6e281551dfe2089679e8e5eb.camel@infradead.org> <944ddefdc0ef3dc0f78c7957afa7f12e360a4392.camel@infradead.org> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-7P6HBZxPS6y0BS5l3bkj" User-Agent: Evolution 3.52.3-0ubuntu1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by desiato.infradead.org. See http://www.infradead.org/rpr.html --=-7P6HBZxPS6y0BS5l3bkj Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2025-05-05 at 16:32 -0700, David Woodhouse wrote: >=20 > Thanks. Should I be expecting this to work...? >=20 > qemu-system-x86_64 -display none -vga none=C2=A0 -accel kvm,kernel-irqchi= p=3Dsplit \ > =C2=A0 -kernel arch/x86/boot/bzImage \ > =C2=A0 -append "console=3DttyS4 root=3D/dev/vda1 earlyprintk=3Dpciserial"= \ > =C2=A0 -chardev stdio,mux=3Don,id=3Dchar0,signal=3Doff -mon char0 -device= pci-serial,chardev=3Dchar0 Hm, no, qemu's pci-serial is PIO. I'd need to do this: --- a/hw/char/serial-pci.c +++ b/hw/char/serial-pci.c @@ -58,7 +58,7 @@ static void serial_pci_realize(PCIDevice *dev, Error **er= rp) s->irq =3D pci_allocate_irq(&pci->dev); =20 memory_region_init_io(&s->io, OBJECT(pci), &serial_io_ops, s, "serial"= , 8); - pci_register_bar(&pci->dev, 0, PCI_BASE_ADDRESS_SPACE_IO, &s->io); + pci_register_bar(&pci->dev, 0, PCI_BASE_ADDRESS_SPACE_MEMORY, &s->io); } =20 static void serial_pci_exit(PCIDevice *dev) And then the kernel's 'earlyprintk=3Dpciserial' needs to be told the BDF, e.g. earlyprintk=3Dpciserial,00:03.0,keep And it's still defaulting to mmio32 unless I do this in the kernel... --- a/arch/x86/kernel/early_printk.c +++ b/arch/x86/kernel/early_printk.c @@ -198,7 +198,7 @@ static __init void early_serial_init(char *s) =20 static __noendbr void mem32_serial_out(unsigned long addr, int offset, int= value) { - u32 __iomem *vaddr =3D (u32 __iomem *)addr; + u8 __iomem *vaddr =3D (u8 __iomem *)addr; /* shift implied by pointer type */ writel(value, vaddr + offset); } @@ -206,7 +206,7 @@ ANNOTATE_NOENDBR_SYM(mem32_serial_out); =20 static __noendbr unsigned int mem32_serial_in(unsigned long addr, int offs= et) { - u32 __iomem *vaddr =3D (u32 __iomem *)addr; + u8 __iomem *vaddr =3D (u8 __iomem *)addr; /* shift implied by pointer type */ return readl(vaddr + offset); } If you can get this part working sanely, I'll happily add the kexec debug p= art. --=-7P6HBZxPS6y0BS5l3bkj Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCD9Aw ggSOMIIDdqADAgECAhAOmiw0ECVD4cWj5DqVrT9PMA0GCSqGSIb3DQEBCwUAMGUxCzAJBgNVBAYT AlVTMRUwEwYDVQQKEwxEaWdpQ2VydCBJbmMxGTAXBgNVBAsTEHd3dy5kaWdpY2VydC5jb20xJDAi BgNVBAMTG0RpZ2lDZXJ0IEFzc3VyZWQgSUQgUm9vdCBDQTAeFw0yNDAxMzAwMDAwMDBaFw0zMTEx MDkyMzU5NTlaMEExCzAJBgNVBAYTAkFVMRAwDgYDVQQKEwdWZXJva2V5MSAwHgYDVQQDExdWZXJv 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