Date: Wed, 28 Mar 2007 14:52:44 -0700 From: Marcel Moolenaar <xcllnt@mac.com> To: Ben Kaduk <minimarmot@gmail.com> Cc: cvs-src@freebsd.org, Marcel Moolenaar <marcel@freebsd.org>, src-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/dev/uart uart_core.c Message-ID: <CF0AD72B-3E7B-48CA-876B-BC3F2CEA3394@mac.com> In-Reply-To: <47d0403c0703281419n22d73ba0u528df488bc8afc8b@mail.gmail.com> References: <200703281826.l2SIQDTN060321@repoman.freebsd.org> <47d0403c0703281419n22d73ba0u528df488bc8afc8b@mail.gmail.com>
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On Mar 28, 2007, at 2:19 PM, Ben Kaduk wrote: > On 3/28/07, Marcel Moolenaar <marcel@freebsd.org> wrote: >> marcel 2007-03-28 18:26:12 UTC >> >> FreeBSD src repository >> >> Modified files: >> sys/dev/uart uart_core.c >> Log: >> When we match UARTs found during bus-enumeration with UARTs used >> for >> system devices (i.e. console, debug port or keyboard), don't stop >> after the first match. Find them all and keep track of the last. >> The reason for this change is that the low-level console is always >> added to the list of system devices first, with other devices added >> later. Since new devices are added to the list at the head, we have >> the console always at the end. When a debug port is using the same >> UART as the console, we would previously mark the "newbus" UART as >> a debug port instead of as a console. This would later result in a >> panic because no "newbus" device was associated with the console. >> By matching all possible system devices we would mark the "newbus" >> UART as a console and not as a debug port. >> While it is arguably better to be able to mark a "newbus" UART as >> both console and debug port, this fix is lightweight and allows >> a single UART to be used as the console as well as a debug port >> with only the aesthetic bug of not telling the user about it also >> being a debug port. >> > > I am rather ignorant about such things, but is there any security risk > in having an "undocumented" debug port? There's no security issue. The user/administrator has to configure the machine and/or kernel before there will be a UART-based debug port. The kernel will announce when uart is used as a debug port. There's just a particular case when the uart port in question will not announce that it's the debug port. FYI, -- Marcel Moolenaar xcllnt@mac.com
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