Date: Fri, 24 Jan 2025 09:34:19 -0700 From: Warner Losh <imp@bsdimp.com> To: Garrett Wollman <wollman@bimajority.org> Cc: Freebsd-stable List <stable@freebsd.org> Subject: Re: not working /dev/console Message-ID: <CANCZdfp-WKoLttgbtNErXWp1TC25evyiPjf67RsSpB0SCXC=4g@mail.gmail.com> In-Reply-To: <26515.47972.648957.594263@hergotha.csail.mit.edu> References: <DBE9ABDF-092F-4198-9E14-DF2E0AAB3638@cs.huji.ac.il> <Z0bcQvu36o-rqsJn@fc.opsec.eu> <CAA78225-E266-4CBE-807D-B72D9BCE58E8@cs.huji.ac.il> <CANCZdfoQtYLP62rWO6oTHg4ajbV7SK=ehq2jkv1o0ZX8_im0jw@mail.gmail.com> <365D866D-F7D2-4DB6-AFFB-B4C3829D8467@cs.huji.ac.il> <CANCZdfoiJE6-aKKFhafXPMY8FOg4nEBmhf2hN%2BcJXzMVrkyiqg@mail.gmail.com> <26514.45659.142313.471958@hergotha.csail.mit.edu> <CANCZdfp5vJag=z%2Bf-zgWpdxtTZ12xHGGsses5qrCokEZSmSymg@mail.gmail.com> <26515.47972.648957.594263@hergotha.csail.mit.edu>
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--0000000000001a2fd2062c764d6e Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, Jan 24, 2025 at 9:10=E2=80=AFAM Garrett Wollman <wollman@bimajority= .org> wrote: > <<On Thu, 23 Jan 2025 23:50:26 -0700, Warner Losh <imp@bsdimp.com> said: > > > On Thu, Jan 23, 2025, 2:19=E2=80=AFPM Garrett Wollman <wollman@bimajori= ty.org> > > wrote: > > >> Resurrecting an old thread, because I find myself in a position where > >> I have to get a serial console working on a UEFI-only Dell R360 (with > >> iDRAC Express, so no remote video console that I can look at). > >> > > > What version? > > We're on 13.4. We hope to go to 14 in the summer. > Both 13 and 14 have trouble with the latest batch of EDK-2 systems that public a SPCR table to describe the serial ports. 15 has support for that baked in fairly well, though. It's needed for arm64 systems a lot, but amd64 systems are popping up that need it. Maybe this is one. > >> OK efi-show -v ConOut > >> global NV,BS,RS ConOut =3D > >> > PciRoot(0x0)/Pci(0x1C,0x4)/Pci(0x0,0x0)/Pci(0x0,0x0)/AcpiAdr(0x80010100),= /PciRoot(0x0)/Pci(0x1F,0x0)/Serial(0x0)/Uart(115195,8,N,1)/VenVt100() > >> > > > Odd band rate. Makes me suspect serial clock rate. But this is from the > > bios.. > > Yes, I'm puzzled about that (and I'm certain that in the BIOS setup it > does not say 115195). Does the kernel care about the baud rate from > EFI not matching the configuration? > No. But it's a tell-tale sign that someone has done 'math' based on divisors and clock rates to come up with this number rather than having this number drive the divisor. And only the latest systems are doing *that* from what I've seen. The difference between 115200 and 115195 in terms of baud-rate divisors is nothing, and even if it were something, the difference between those two baud rates is well within the 1% tolerance that UARTs have. Warner --0000000000001a2fd2062c764d6e Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr"><div dir=3D"ltr"><br></div><br><div class=3D"gmail_quote g= mail_quote_container"><div dir=3D"ltr" class=3D"gmail_attr">On Fri, Jan 24,= 2025 at 9:10=E2=80=AFAM Garrett Wollman <<a href=3D"mailto:wollman@bima= jority.org">wollman@bimajority.org</a>> wrote:<br></div><blockquote clas= s=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid r= gb(204,204,204);padding-left:1ex"><<On Thu, 23 Jan 2025 23:50:26 -070= 0, Warner Losh <<a href=3D"mailto:imp@bsdimp.com" target=3D"_blank">imp@= bsdimp.com</a>> said:<br> <br> > On Thu, Jan 23, 2025, 2:19=E2=80=AFPM Garrett Wollman <<a href=3D"m= ailto:wollman@bimajority.org" target=3D"_blank">wollman@bimajority.org</a>&= gt;<br> > wrote:<br> <br> >> Resurrecting an old thread, because I find myself in a position wh= ere<br> >> I have to get a serial console working on a UEFI-only Dell R360 (w= ith<br> >> iDRAC Express, so no remote video console that I can look at).<br> >> <br> <br> > What version?<br> <br> We're on 13.4.=C2=A0 We hope to go to 14 in the summer.<br></blockquote= ><div><br></div><div>Both 13 and 14 have trouble with the latest batch of E= DK-2 systems that public a SPCR table to describe the serial ports. 15 has = support for that baked in fairly well, though. It's needed for arm64 sy= stems a lot, but amd64 systems=C2=A0are popping up that need it. Maybe this= is one.</div><div>=C2=A0</div><blockquote class=3D"gmail_quote" style=3D"m= argin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left= :1ex"> >> OK efi-show -v ConOut<br> >> global NV,BS,RS ConOut =3D<br> >> PciRoot(0x0)/Pci(0x1C,0x4)/Pci(0x0,0x0)/Pci(0x0,0x0)/AcpiAdr(0x800= 10100),/PciRoot(0x0)/Pci(0x1F,0x0)/Serial(0x0)/Uart(115195,8,N,1)/VenVt100(= )<br> >> <br> <br> > Odd band rate. Makes me suspect serial clock rate. But this is from th= e<br> > bios..<br> <br> Yes, I'm puzzled about that (and I'm certain that in the BIOS setup= it<br> does not say 115195).=C2=A0 Does the kernel care about the baud rate from<b= r> EFI not matching the configuration?<br></blockquote><div><br></div><div>No.= But it's a tell-tale sign that someone has done 'math' based o= n divisors and clock rates to come up with this number rather than having t= his number drive the divisor. And only the latest systems are doing *that* = from what I've seen. The difference between 115200 and 115195 in terms = of baud-rate divisors is nothing, and even if it were something, the differ= ence between those two baud rates is well within the 1% tolerance that UART= s have.</div><div><br></div><div>Warner=C2=A0</div></div></div> --0000000000001a2fd2062c764d6e--
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