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Bigmem enabled on amd64
Contributed by jj on Wed Apr 13 11:19:51 2011 (GMT)
from the half-meg-half-gig-half-tera dept.

Since this commit:

代码: 全选

CVSROOT:    /cvs
    Module name:    src
    Changes by:    [email protected]    2011/04/02 11:36:45
 
    Modified files:
        sys/arch/amd64/amd64: machdep.c 
 
    Log message:
    Enable bigmem by default on amd64.
    ok deraadt@

amd64 machines may now use more than 4G of ram.

Given the fact that amd64 machines commonly have more than 4G (or rather the 3.5G you end up getting usable after everything else has been deducted) nowadays, this is really good news.

It has required some changes to the buffer cache in order for it to only pick memory in the low 4G range for I/O buffers, and similar changes to various other device drivers, but apart from that, it is ready for testing by you!

I took a few of my local amd64 machines for a spin and they all ran as expected so I decided to take a box at work for a quick run. It got stuck here for a long while before continuing on to this dmesg.

The whole installation went fine, with a record comp49.tgz unpack in 7 seconds (probably attributed to the fast disks more than the memory) but unfortunately, the final installation when booted with all 64 cores and 512G memory enabled left me with these crashes.

I don't have access to the box anymore, so I couldn't test with a bunch of cores (or HT) disabled, but at least the whole installation (which does run in single-processor mode) went through, so there's definitely hope even for big boxes. I have no idea how OpenBSD scales, but if anyone buys me another one of these lovely Dell 910 boxes, I'll surely find out.

>
(4) grub started fine, and Windows XP boots fine, but when I try to
boot OpenBSD, I get something like this:
Loading...
probing: <<additional details>>
disk: fd0 hd0+*
>> OpenBSD/i386 BOOT 2.13
open(hd0a:/etc/boot.conf): Invalid argument
boot>
booting hd0a:/bsd: open hd0a:/bsd: Invalid argument
failed(22). will try ...
And OpenBSD never boots. I don't recall changing anything else. From
what I know (very little), biosboot was able to load the 2nd stage
bootloader, but it now failed loading the kernel image.

What surprises me is OpenBSD booted fine *before* I had Windows XP,
and the ~143G partition was still present. Possibly something else is
broken...

Nope. We introduced a hard limit of 128GB as the workable lowest common
denominator while we research a reliable way to determine when it is
safe to go beyond. On one of my recent machines, just to pick an example,
the BIOS simply returns all zero's for all I/O attempted past 128GB.

We do like to impose draconian new restrictions and debug code early
in a release cycle. :-)

The lack of a reliable way to safely go beyond 128GB, even with recent
BIOSen is sad and no doubt the reason Windows wants the first 100MB or
so for its boot, OpenSUSE 11.4 blew up when installed >128GB on a
just purchased motherboard, etc.

The second target for anyone with a time machine should be the morons
who decided BIOS would be enough for anyone.

>
> "makeactive" in menu.lst for grub did not help either (as I had guessed).
>
> -Amarendra
> [...]
>

All grub can do (to my knowledge) is grab and run the OpenBSD /boot
program. And if it doesn't work ...

.... Ken

You need to compile 'and friends', in particular a new /boot. And
install it. This is done by

cd /usr/src/sys/arch/[1386|amd64]/stand
make clean
make obj
make
make install
/usr/mdec/installboot -v /boot /usr/mdec/biosboot

all as root of course.

# /usr/mdec/installboot -v /boot /usr/mdec/biosboot sd0