Date: Wed, 28 Mar 2007 16:19:51 -0500 From: "Ben Kaduk" <minimarmot@gmail.com> To: "Marcel Moolenaar" <marcel@freebsd.org> Cc: cvs-src@freebsd.org, src-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/dev/uart uart_core.c Message-ID: <47d0403c0703281419n22d73ba0u528df488bc8afc8b@mail.gmail.com> In-Reply-To: <200703281826.l2SIQDTN060321@repoman.freebsd.org> References: <200703281826.l2SIQDTN060321@repoman.freebsd.org>
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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? I am under the impression that debug ports can do such things as break to the debugger and access arbitrary memory, which a console is not guaranteed to be able to do. -Ben Kaduk [snip]
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