Date: Tue, 24 Jan 2023 22:12:14 GMT From: Warner Losh <imp@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: adeec17f8122 - stable/13 - stand: Document that boot0 uses BIOS Message-ID: <202301242212.30OMCEsE086751@gitrepo.freebsd.org>
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The branch stable/13 has been updated by imp: URL: https://cgit.FreeBSD.org/src/commit/?id=adeec17f8122f9af4940e6e45391b38b377082c1 commit adeec17f8122f9af4940e6e45391b38b377082c1 Author: Warner Losh <imp@FreeBSD.org> AuthorDate: 2022-08-26 21:47:21 +0000 Commit: Warner Losh <imp@FreeBSD.org> CommitDate: 2023-01-24 21:49:32 +0000 stand: Document that boot0 uses BIOS And thus has a limited range of supported baud rates. Also add that setting BOOT_BOOT0_COMCONSOLE_SPEED=0 will leave it unchanged which sometimes can give you 115200 if the BIOS initialized things outside of the normal BIOS baud rates (which many x86 enbedded-targetted boards do). Sponsored by: Netflix Reviewed by: emaste, manu (earlier versions) Suggestions by: jhb Differential Revision: https://reviews.freebsd.org/D36300 (cherry picked from commit 7ed3228323ef4f9e3130603ea68c3be9c2ed50ce) --- stand/i386/boot0/Makefile | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/stand/i386/boot0/Makefile b/stand/i386/boot0/Makefile index 82eb9eefee76..1453f17751b9 100644 --- a/stand/i386/boot0/Makefile +++ b/stand/i386/boot0/Makefile @@ -42,6 +42,13 @@ BOOT_BOOT0_ORG?= 0x600 ORG=${BOOT_BOOT0_ORG} # Comm settings for boot0sio. +# +# boot0sio uses BIOS INT $0x14 for serial ports, we can only support these +# baudrates due to INT14's limited interface. In addition, if +# BOOT_BOOT0_COMCONSOLE_SPEED=0, then the baud rate and frame format will remain +# unchanged. Some BIOSes initialize the serial ports to 115200, and this may +# allow boot0sio access at that rate if so. +# # Bit(s) Description # 7-5 data rate (110,150,300,600,1200,2400,4800,9600 bps) # 4-3 parity (00 or 10 = none, 01 = odd, 11 = even)
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