From mboxrd@z Thu Jan 1 00:00:00 1970 From: clemc@ccc.com (Clem Cole) Date: Sun, 8 Feb 2015 18:45:35 -0500 Subject: [TUHS] 2.9BSD on an actual rl02 - swap confusion In-Reply-To: <20150208224209.6AB7718C0BE@mercury.lcs.mit.edu> References: <20150208224209.6AB7718C0BE@mercury.lcs.mit.edu> Message-ID: On Sun, Feb 8, 2015 at 5:42 PM, Noel Chiappa wrote: > But this is kind of confusing, because when I was bringing up V6 under the > Ersatz11 simulator, I had a problem where the swapper (process 0) was > trying > to fork (with the child becoming 1 and running /etc/init), and it did the > 'swap out' thing. But there was a ton of free memory at that point, so... > why > was it doing a swap? Eh, something to investigate sometime... > ​I'm relying on very old memory here ... but my memory is that before either fork or exec or maybe both (I forget all of this and don't have the code on my laptop to check) the kernel did something in the swap area/maps. It may have been just preallocate the data area for the process. ​But if there was not enough space/got an error of some type, the system call failed. What this meant was the even if you has free ram, you had to have a working swap device very early in the start up. I wish I could remember those details - hard to believe I spent so many hours (of fun) hacking on the kernel of those systems ;-) Clem -------------- next part -------------- An HTML attachment was scrubbed... URL: