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)
