From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3D112024.E4B7C59D@opersys.com> Date: Thu, 20 Jun 2002 00:21:56 +0000 From: Karim Yaghmour Reply-To: karim@domain.hid MIME-Version: 1.0 Subject: Re: [Adeos-main] Address spaces in adeos References: <3D0F0BA2.969434A3@domain.hid> <20020619051755.75505.qmail@domain.hid> <15632.30733.393799.700979@domain.hid> <20020619130256.GA1529@domain.hid> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: adeos-main-admin@domain.hid Errors-To: adeos-main-admin@domain.hid List-Help: List-Post: List-Subscribe: , List-Id: List-Unsubscribe: , List-Archive: To: Jacob Gorm Hansen Cc: adeos-main@gna.org Hello Jacob, Jacob Gorm Hansen wrote: > do you guys have any plans to implement protected address spaces, and means of > communicating between them (like ipc)? There are some scenarios in which > operating systems cannot be trusted not to sabotage eachother. This is one of the scenarios which was discussed in the original announcement. It is foreseeable, for instance, to have 2 OSes running in the same RAM, each within its own physical boundaries: Kernel A: 0-64MB Kerbel B: 64-128MB As with other nanokernels, the main mechanism to communicate between such kernels would be soft interrupts. We could even foresee another scenario where there's one part of the RAM that is reserved for setting up shared memory regions between OSes. There are 2 main "problems" in all these such scenarios: 1- There is no protection for physical accesses since all OSes have can directly play with the hardware. 2- Page faults must be sent to the faulty domain only. #2 is not really that hard to solve. We need to implement a page fault demux which sends the page fault to the current domain only. There is, unfortunately, no real way to get around #1 without adding extra virtualization layers. Since we are assuming stable kernels with "intelligent" code, however, then it should not be a problem. Karim =================================================== Karim Yaghmour karim@domain.hid Embedded and Real-Time Linux Expert ===================================================