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A comment on The Sad Saga of Purism and the Librem 5. Parent comment

Re:The Sad Saga of Purism and the Librem 5 by mondoshawan on Sunday October 27, 2019 @12:42PM (#21370789)
Sadly, the modems are on PCIe, so this means they are sharing memory and address space with the host iMX8.
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Re:The Sad Saga of Purism and the Librem 5 by moosingin3space on Monday October 28, 2019 @03:21AM (#21374932)
You can use an IOMMU to isolate DMA to a separate security domain. This is how Qubes OS works.
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Re:The Sad Saga of Purism and the Librem 5 by mondoshawan on Monday October 28, 2019 @10:24AM (#21377276)
No iommu on the imx8mq.
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Re:The Sad Saga of Purism and the Librem 5 by moosingin3space on Monday October 28, 2019 @02:32PM (#21380027)
That's unfortunate, since an IOMMU is an excellent solution to this kind of problem, especially when one considers all the potential Linux USB stack vulnerabilities that can be exploited if you assume the modem is untrustworthy.
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Re:The Sad Saga of Purism and the Librem 5 by V4ASt2 on Sunday October 27, 2019 @01:40PM (#21371178)
Sadly, you're wrong, and the phone modem is on the USB bus precisely for that reason.
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Re:The Sad Saga of Purism and the Librem 5 by mondoshawan on Sunday October 27, 2019 @01:44PM (#21371200)
Sadly I am happy to be corrected! :D
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Re:The Sad Saga of Purism and the Librem 5 by djsumdog on Sunday October 27, 2019 @01:03PM (#21370924)
Yea, if feels like if you wanted that kind of isolation, you'd actually need a second SoC on there with its own memory and some kind of communication back to the main processor.
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