Date: Mon, 1 Dec 2008 13:58:15 -0500 From: John Baldwin <jhb@freebsd.org> To: Luigi Rizzo <luigi@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r185339 - head/sys/boot/i386/boot0 Message-ID: <200812011358.15430.jhb@freebsd.org> In-Reply-To: <200811261801.mAQI1LRp062260@svn.freebsd.org> References: <200811261801.mAQI1LRp062260@svn.freebsd.org>
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On Wednesday 26 November 2008 01:01:21 pm Luigi Rizzo wrote: > Author: luigi > Date: Wed Nov 26 18:01:21 2008 > New Revision: 185339 > URL: http://svn.freebsd.org/changeset/base/185339 > > Log: > Pass the pointer to the selected partition in %si to the next stage > boot code. The bug was introduced in rev.1.13, and went unnoticed > because FreeBSD's boot1 does not use it, but other systems might. > > (I have been struggling for almost a full day trying to figure out > why a syslinux'ed partition would not boot when started with the > FreeBSD /boot/boot0, only to realize that the bug was ours!) > > The space for the two extra bytes (push %si and pop %si) is reclaimed > by removing an extra CRLF that is printed before booting. > > The bug is not a major one but if there is time it might be a good > thing to merge it into the upcoming releases. Note that there is nothing (no standard, etc.) that requires any MBR boot loader to pass anything besides %dl (boot device ID) to other loaders. However, we did used to do this and had an 'XXX: what does %si carry?' comment that 1.13 removed. I would suggest adding a more expanded comment about '%si' in the block comment above this code where the old 'XXX' comment was detailing why %si is preserved. -- John Baldwin
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