Hi, > as far as Tails is concerned, I'm thinking of: > - on 64-bit hardware, kexec to a 64-bit kernel and use memtest= > there; Maxim, have you confirmed by actual testing this works for > more than 3GB?
I have confirmed that KEXEC-ing from 32-bit kernel into 64-bit one works, and that memtest covered all of 1.5 GiB that QEMU was provided with, but since it's 64-bit kernel with no concept of high memory, I doubt there is any actual limit. > - on 32-bit hardware, kexec to a 32-bit kernel and go on using > sdmem; it's still limited to 3GB, but arguably 32-bit computers > with more than 3GB of RAM are very rare. See my other email — you can use 1G/3G VMSPLIT in the 32-bit KEXEC kernel, and cover a bit less than 3 GiB with memtest. I tested with 1.5 GiB, and memtest covered all of it. Running without memtest (so that QEMU doesn't try to use the allocated memory) with 3 GiB RAM, LOWMEM is 2939 MiB, and HIGHMEM 131 MiB — so it's the previous ~895 MiB we've seen + added 2 GiB due to changed VMSPLIT. To summarize, using memtest + 1G/3G VMSPLIT is comparabled to sdmem (~130 MiB less), but likely more robust. And I agree that one would need to try very hard in order to find 32-bit CPUs with more than even 2 GiB on motherboard. Best regards, Maxim -- Maxim Kammerer Liberté Linux (discussion / support: http://dee.su/liberte-contribute) _______________________________________________ tails-dev mailing list [email protected] https://mailman.boum.org/listinfo/tails-dev
