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The summary, approximately: there are some crashes detected by Firefox and it seems Firefox (or whatever Firefox uses as its libraries) thinks it can use AVX i
by acqq 10y ago
The summary, approximately: there are some crashes detected by Firefox and it seems Firefox (or whatever Firefox uses as its libraries) thinks it can use AVX instructions even if the OS isn't aware of the AVX technology and therefore can't preserve the content of the registers during its "normal work."
And yuhong has found that the reason Firefox thinks that, specifically on Windows XP which is booted with the Windows 10 loader, is that the Windows 10 loader sets some bit "I know about AVX" instead of clearing it before entering in Windows XP.
- wadkar 10y agoYes, that's been my reading as well.
- yuhong 10y agoSet it then forgot to clear it. The "bits" include CR4.OSXSAVE and XCR0 (set by XSETBV). BOOTMGR is used for booting Vista and later, and it chains to NTLDR for booting XP/Server 2003 and older.
- 0x0 10y agoWindows has always had the worst dualboot story. It'll gladly overwrite grub etc without asking (to "helpfully" fix boot problems?), but if your partitions are ordered a little out of the ordinary it'll still throw a ridiculously not-helpful error. They might as well just stop pretending to support it.
- ivank 10y agoThis took me a while to figure out, but if you use UEFI, and have Windows and Linux on different drives / different EFI system partitions, you can use grub-install --force-extra-removable to keep Linux bootable after Windows helpfully clears out the NVRAM Boot* variables: https://github.com/ludios/ubuntils/blob/master/bin/reinstall-efi-grub https://github.com/ludios/ubuntils/blob/master/bin/reinstall...
- Ezhik 10y agoI legit just physically disconnect the drives with other operating systems while installing Windows in dual boot situations. Can't break what isn't there!
- slavik81 10y agoSometimes very necessary. Windows 7 had a bug that caused it to spread boot information across multiple drives if you had more than one plugged in at install time, even if you specified only to use one.
- ivank 10y agoThat worked with MBR boot, but with UEFI, Windows will notice you have Boot* variables in motherboard NVRAM pointing to a Linux install that doesn't exist, then clear them for you.
- Smushman 10y agoSeems legit... nice summary.