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i am not affiliated with FSF in any way. yet it seems to me that there are plenty of people arguing against them in very bad faith. here is the full excerpt in
by medo-bear 5y ago
i am not affiliated with FSF in any way. yet it seems to me that there are plenty of people arguing against them in very bad faith. here is the full excerpt in question:
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>CPUs supported:
>AMD Opteron 6100 series (Fam10h. No IOMMU support. Not recommended - old. View errata datasheet here: http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf)
>AMD Opteron 6200 series (Fam15h, with full IOMMU support in libreboot - highly recommended - fast, and works well without microcode updates, including virtualization)
>AMD Opteron 6300 series (Fam15h, with full IOMMU support in libreboot. AVOID LIKE THE PLAGUE - virtualization is broken without microcode updates.
>NOTE: 6300 series CPUs have buggy microcode built-in, and libreboot recommends avoiding the updates. The 6200 series CPUs have more reliable microcode. Look at this errata datasheet: http://support.amd.com/TechDocs/48063_15h_Mod_00h-0Fh_Rev_Guide.pdf http://support.amd.com/TechDocs/48063_15h_Mod_00h-0Fh_Rev_Gu... (see Errata 734 - this is what kills the 6300 series)
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source: https://libreboot.org/docs/hardware/kgpe-d16.html https://libreboot.org/docs/hardware/kgpe-d16.html
the Errata 734 is quoted here as reference:
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>734 Processor May Incorrectly Store VMCB Data
>Description: Under a highly specific and detailed set of internal timing conditions during a #VMEXIT for a virtual guest that has multiple virtual CPUs, the processor may store incorrect data to the virtual machine control (VMCB) reserved and guest save areas and may also store outside of the VMCB.
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- mindslight 5y agoIf you are referring to me, I don't see how my excerpt is incomplete or could be seen as bad faith. Libreboot is steering people away from 6300 processors because using them requires explicitly loading a proprietary blob, while encouraging the use of 6200 processors that have an analogous blob baked in at the factory. The real difference is that the former makes you more aware of the compromise.
- medo-bear 5y agoreading the full excerpt seems to put the reason for rejecting 6300 onto Errata 734 and it was strange to me that this wasnt addressed in your post however i wasnt referring to you specifically as arguing in bad faith but that seems to be the attitude of some very vocal people here. i included the full excerpt in case the point is relevant. i am not an expert in this field does the issue in Erata 734 apply to 6200?
- mindslight 5y ago> reading the full excerpt seems to put the reason for rejecting 6300 onto Errata 734 Well there are two reasons. The first is Errata 734, and the second is that the fix for Errata 734 requires loading different microcode than what was baked into the processor at manufacturing time ("6300 series CPUs have buggy microcode built-in, and libreboot recommends avoiding the updates"). I didn't mention Errata 734, because I'm focused on the second reason. Working back from their reasoning, Errata 734 seemingly does not apply to the 6200 series.
- medo-bear 5y agomindslight, i cant reply to you directly so i will do it like this. thank you for clarifying about Erata 734. if Erata 734 applied to 6200 then libreboots logic would make no sense i take no issue about with critically discussing someones logic. fud and attacks are annoying and dont contribute to a healthy discussion