So much for the embargo period. I guess the bsd people were not so wrong after all. They might as well just had published it as soon as it was found.
Microsoft disables Spectre mitigations as Intel’s patches cause instability
51–60 of 329 posts
Re: Microsoft disables Spectre mitigations as Intel’s patches cause instability
#52Earlier quoted context omitted.
There is a very fundamental difference between how Unix and Windows view open files: On Windows, once the file is open, it is that filename that is open; You can't rename or delete it; Therefore, if you want to replace a DLL (or any other file) that is in use, you have to kill any program that uses it before you can do that; And if it's a fundamental library everything uses (USER32.DLL COMCTL.DLL etc), the only effec…
> On Windows, once the file is open, it is that filename that is open; You can't rename or delete it; This is wrong... there's no clear-cut thing like the "file name" or "file stream" that you can specify as "in-use". It depends on the specifics of how the file is opened; often you can rename but not delete files that are open. Some (but AFAIK not all) in-use DLLs are like this. They can be renamed but not deleted. A…
Yes, in principle what you've said about the Unix approach here is correct, if you upgrade one half of a system and not the other half and now they're talking different protocols, that might not work.
But keep in mind that if your system can't cope with this what you've done there is engineer in unreliability, you've made a system that's deliberately not very robust, unless it's very, very tightly integrated (e.g. two sub-routines inside the same running program) the cost savings had better be _enormous_ or what you're doing is just amplifying a problem and giving it to somebody else, like "solving" a city's waste problem by just dumping all the raw sewage into a neighbouring city's rivers.
Now, the "you can't delete things because then the disk space is unreachable" argument makes plenty of sense for, say, FAT, a filesystem from the 1980s.
But (present year argument) this is 2018. Everybody's main file systems are journalled. Sure enough, both systems _can_ write a record to the journal which will cause the blocks to be freed on replay and then remove that journal entry if the blocks actually get freed up before then. The difference is that Windows doesn't bother doing this.
Re: Microsoft disables Spectre mitigations as Intel’s patches cause instability
#53Earlier quoted context omitted.
Speaking of which, why do so many things require reboot to update on Windows?
There is a very fundamental difference between how Unix and Windows view open files: On Windows, once the file is open, it is that filename that is open; You can't rename or delete it; Therefore, if you want to replace a DLL (or any other file) that is in use, you have to kill any program that uses it before you can do that; And if it's a fundamental library everything uses (USER32.DLL COMCTL.DLL etc), the only effec…
> On Windows, once the file is open, it is that filename that is open; You can't rename or delete it
You can rename a file when it's open. And once it's renamed, you can delete it.
Re: Microsoft disables Spectre mitigations as Intel’s patches cause instability
#54Earlier quoted context omitted.
There is a very fundamental difference between how Unix and Windows view open files: On Windows, once the file is open, it is that filename that is open; You can't rename or delete it; Therefore, if you want to replace a DLL (or any other file) that is in use, you have to kill any program that uses it before you can do that; And if it's a fundamental library everything uses (USER32.DLL COMCTL.DLL etc), the only effec…
> On Windows, once the file is open, it is that filename that is open; You can't rename or delete it; This is wrong... there's no clear-cut thing like the "file name" or "file stream" that you can specify as "in-use". It depends on the specifics of how the file is opened; often you can rename but not delete files that are open. Some (but AFAIK not all) in-use DLLs are like this. They can be renamed but not deleted. A…
> What I expect it also means is that you'll get inconsistencies when doing inter-process communication, since they'll be using different libraries with potential mismatches. Is this correct?
Only if the libraries that use IPC have changed their wire format between versions, which would be a pretty bad practice, so I wouldn't expect that to happen often (if ever).
If something that's already running has its data files moved around or changed sufficiently, and it later tries to open (that is, the app was running but the data file wasn't open when the upgrade happened) what it thinks is an old data file, but is either new and different or just missing, that could cause problems.
> Because it seems to me that the Windows method might be less flexible but is likely to be more stable, since there's a single coherent global view of the file system at any given time.
In practice I've never had an issue with this (nearly 20 years using various Linux desktop and server distros). Upgrade-in-place is generally the norm, and most people will only reboot if there's a kernel update or an update to the init system.
Re: Microsoft disables Spectre mitigations as Intel’s patches cause instability
#55Earlier quoted context omitted.
There is a very fundamental difference between how Unix and Windows view open files: On Windows, once the file is open, it is that filename that is open; You can't rename or delete it; Therefore, if you want to replace a DLL (or any other file) that is in use, you have to kill any program that uses it before you can do that; And if it's a fundamental library everything uses (USER32.DLL COMCTL.DLL etc), the only effec…
> On Windows, once the file is open, it is that filename that is open; You can't rename or delete it; This is wrong... there's no clear-cut thing like the "file name" or "file stream" that you can specify as "in-use". It depends on the specifics of how the file is opened; often you can rename but not delete files that are open. Some (but AFAIK not all) in-use DLLs are like this. They can be renamed but not deleted. A…
> What I expect it also means is that you'll get inconsistencies when doing inter-process communication, since they'll be using different libraries with potential mismatches.
In theory, but Linux systems tend to do very little IPC other than X11, pipelines, and IP-based communication, where the protocols tend to support running with different versions.
In practice you can achieve multi-year uptimes with systems until you get a mandatory kernel security update.
Re: Microsoft disables Spectre mitigations as Intel’s patches cause instability
#56It is not only Microsoft reverting this patch. HP, Dell or Red Hat are doing that as well.
https://www.bleepingcomputer.com/news/microsoft/microsoft-is...
Re: Microsoft disables Spectre mitigations as Intel’s patches cause instability
#57Earlier quoted context omitted.
There is a very fundamental difference between how Unix and Windows view open files: On Windows, once the file is open, it is that filename that is open; You can't rename or delete it; Therefore, if you want to replace a DLL (or any other file) that is in use, you have to kill any program that uses it before you can do that; And if it's a fundamental library everything uses (USER32.DLL COMCTL.DLL etc), the only effec…
> On Windows, once the file is open, it is that filename that is open; You can't rename or delete it; This is wrong... there's no clear-cut thing like the "file name" or "file stream" that you can specify as "in-use". It depends on the specifics of how the file is opened; often you can rename but not delete files that are open. Some (but AFAIK not all) in-use DLLs are like this. They can be renamed but not deleted. A…
*nixes have a system for handing off to the newer version such as kpatch and kgraft.
kgraft for example swaps off each syscall for a process while it is not being used. This lets the OS slowly transfer to the new kernel as it is running.
kpatch does it all in one go but locks up the system for a few milliseconds.
The version that is currently merged into 4.0+ kernels is a hybrid of the two developed by the authors of both systems.
Re: Microsoft disables Spectre mitigations as Intel’s patches cause instability
#58Earlier quoted context omitted.
> On Windows, once the file is open, it is that filename that is open; You can't rename or delete it; This is wrong... there's no clear-cut thing like the "file name" or "file stream" that you can specify as "in-use". It depends on the specifics of how the file is opened; often you can rename but not delete files that are open. Some (but AFAIK not all) in-use DLLs are like this. They can be renamed but not deleted. A…
> What I expect it also means is that you'll get inconsistencies when doing inter-process communication, since they'll be using different libraries with potential mismatches. In theory, but Linux systems tend to do very little IPC other than X11, pipelines, and IP-based communication, where the protocols tend to support running with different versions. In practice you can achieve multi-year uptimes with systems until…
X11 (or other window-related tooling) was exactly what I was thinking of actually, because every time I do a major Linux (Ubuntu) update I can't really launch programs and use my computer normally until I reboot. It always gets finicky and IPC mismatch is the best explanation I can think of.
Re: Microsoft disables Spectre mitigations as Intel’s patches cause instability
#59Earlier quoted context omitted.
Just in case you, like me, missed the memo where Microsoft said they'd stop supplying security updates if you have no AV / AV incompatible with the patches installed. The fix to the former is creating the registry entry manually. https://support.microsoft.com/en-us/help/4072699/january-3-2...
Bizarre. Customers without Antivirus In cases where customers can’t install or run antivirus software, Microsoft recommends manually setting the registry key as described below in order to receive the January 2018 security updates.
Sounds like Microsoft can't tell the difference between "has AV installed that will break" and "has no AV installed", which makes sense. It's probably infeasible to reliably fingerprint all existing AV software.
Re: Microsoft disables Spectre mitigations as Intel’s patches cause instability
#60I lost many hours over this last week. The system was unable to boot and finally a thread on reddit came to the rescue ( https://www.reddit.com/r/techsupport/comments/7sbihd/howto_f... ). This actually made the system boot but there are some leftovers being installed on first boot that I've been unable to disable that also causes the system to be unable to boot. So now, the machine is running but as soon as it is res…
Speaking of which, why do so many things require reboot to update on Windows?
I used to joke that Windows was alone in this issue, my work laptop being a prime example, but even Apple tends to towards reboots more often than not and especially as of late. Fortunately both can do it during slow periods; as in over night; and make updates nearly invisible to users.