Tip For Repairing Ancient Linux Installations
Here’s the scenario: there is a malfunctioning server running a really ancient Linux installation (e.g. 2.6.x-series kernel). You boot up with a reasonably recent copy of SystemRescue, mount the machine’s filesystem, try to chroot into it and run a shell ... and it segfaults. Seems there has been a subtle incompatible change in Linux kernel behaviour since those times, to do with the disabling of something called the “vsyscall” mechanism (which is specific to 64-bit x86-based machines, I understand). This was supposed to be a way to speed up certain commonly-executed system calls (I think getting the system time was one of them) by allowing direct transfers to certain entry points with fixed memory addresses for invoking them. It was later decided this was a bad idea (I think for security reasons). The mechanism has not been completely removed (yet), but nowadays it is disabled by default. To get around this, you need to boot SystemRescue with a change to the kernel command-line parameters, adding this item vsyscall=emulate After you get to a shell, you can confirm that this setting is in effect by checking the /proc/self/maps file (the memory mappings for your own process). At the bottom, there should be an entry with “[vdso]” in it, and below that another line with “[vsyscall]”. The presence of the latter line indicates that vsyscall emulation is in effect. This is not present when I check a process on my own machine, for example. Linus is legendary for being a stickler for never, ever breaking backward compatibility for userland. So the reasons for turning this off must have been pretty compelling, for him to agree to it. But the compromise is, it’s still there to be enabled if you really, really need it. There’s a bit more technical info here <https://0xax.gitbooks.io/linux-insides/content/SysCall/linux-syscall-3.html>, if you are interested. By the way, the above page is part of a book beginning here <https://0xax.gitbooks.io/linux-insides/content/>, about the insides of the Linux kernel. The whole book seems to be accessible from that link, but if you step up a level, the site doesn’t seem to have any idea about the existence of that book.
What can happen if your accounting software doesn't do the maths correctly (and you can wait 20+ years)... Nine hundred wrongly convicted British post office workers are on their way to getting justice following a public apology from the company that provided the faulty technology that led to their false convictions. Fujitsu director apologises for British Post Office scandal that saw 900 workers wrongly convicted. The British Post Office rolled out the Horizon information technology system, developed by Fujistu, in 1999 to automate sales accounting. Soon after, local post office managers began finding unexplained losses that they were responsible to cover. The state-owned Post Office took Fujistu's side, claiming that Horizon was reliable and that the branch managers were lying. Between 2000 and 2014, around 900 postal workers were wrongly convicted of theft, fraud and false accounting, with some going to prison and others forced into bankruptcy. To date, a total of nearly 150 million pounds has been paid to more than 2,500 victims, Prime Minister Rishi Sunak said. ...and there is now, from ITV, a four-part docudrama, "Mr. Bates vs the Post Office". Mr. Bates has spent nearly two decades trying to expose the scandal and exonerate his peers. https://www.abc.net.au/news/2024-01-17/british-post-office-scandal-fujitsu-a... cheers, Ian.
On 20/01/24 21:34, Ian Stewart wrote:
What can happen if your accounting software doesn't do the maths correctly (and you can wait 20+ years)...
Nine hundred wrongly convicted British post office workers are on their way to getting justice following a public apology from the company that provided the faulty technology that led to their false convictions.
Fujitsu director apologises for British Post Office scandal that saw 900 workers wrongly convicted. ---8<---
It will be interesting to see if there will be any consequences for those who committed the lying/fraud. On the topic of accounting software: What FOSS systems are there around that could do potentially the job that Horizon did? There are the *ledger systems, which use plain text data files and a command line interface which work great for small systems. There is Odoo, which is larger and I understand is used by some NZ companies. Neither of those would be suitable and I imagine that for a lot less than 150M pounds of public money you could make something well suited to the task. Glenn
On Sat, 20 Jan 2024 21:34:18 +1300, Ian Stewart wrote:
...and there is now, from ITV, a four-part docudrama, "Mr. Bates vs the Post Office".
Currently showing on TV1. I think TVNZ is showing two parts at a time, (starting last night) so it concludes tonight.
On 1/04/24 19:34, Lawrence D'Oliveiro wrote:
Currently showing on TV1. I think TVNZ is showing two parts at a time, (starting last night) so it concludes tonight.
The four, 45 minute, episodes of "Mr Bates vs. The Post Office" are now available for watching online for free via TVNZ on demand. This is the link to episode one... https://www.tvnz.co.nz/shows/mr-bates-vs-the-post-office/episodes/s1-e1 cheers, Ian.
participants (3)
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Glenn Ramsey -
Ian Stewart -
Lawrence D'Oliveiro