[HN Gopher] Why doesn't Windows use 64-bit virtual address space... ___________________________________________________________________ Why doesn't Windows use 64-bit virtual address space below 0x00000000`7ffe0000? Author : signa11 Score : 83 points Date : 2022-12-18 06:28 UTC (16 hours ago) (HTM) web link (devblogs.microsoft.com) (TXT) w3m dump (devblogs.microsoft.com) | darknavi wrote: | I enjoy the short and sweet blog posts from Raymond Chen on "Why | does Windows X?". | krylon wrote: | He is great at summing up these things in a way I can | understand (most of the time, not being very experienced with | Windows internals) without having the feeling he is dumbing it | down, just that he is explaining it very clearly. | [deleted] | 082349872349872 wrote: | tl;dr several reasons, the most specific of which is "to keep | linker relocs simple" | alexklarjr wrote: | ...on a long dead architecture. | ourmandave wrote: | Chen is the poster boy for backwards compat. | | They used to work very hard to make sure updates didn't break | popular programs that used undocumented hacks. | AnimalMuppet wrote: | > They used to work very hard to make sure updates didn't | break popular programs that used undocumented hacks. | | Obsessively. | | I worked for a company that sold a security auditing tool. | We cared very much about which version of Windows we were | running on. When Microsoft came out with the next version | of Windows and to our dismay, we found out that our | software recognized it as the old version. | | Turns out that Microsoft had found (pre release) that the | new version broke our software. It reported "unknown | version" or something. So they added us to a long list of | applications that, when those applications asked for what | version of Windows they were running on, Windows lied and | told them an earlier version. | | It cost us some heartburn to work around Windows trying to | be helpful to us... | jasoneckert wrote: | I still have Windows 2000 installed on a Digital Ultimate | Workstation (2x Alpha 21164). I turn it on every few years | when I need a nostalgia kick ;-) | KMag wrote: | So sad to see Alpha die off, especially since I haven't | noticed any architectures with anything like PALCode spring | up since. The Alpha's firmware was essentially a hypervisor | that only supported a single guest, and the OS kernel had | to upcall to the firmware for any privileged operations. | | In particular, it would be nice to have userspace programs | be able to take advantage of new/larger registers without | requiring the OS kernel to support the extra CPU state. If | the firmware (which presumably is available as soon as the | new CPU ships) handles the context switch, then the OS | kernel doesn't need an update. | analog31 wrote: | They need to reserve the first 2147352576 bytes for the Color | Graphics Adapter display buffer. | herpderperator wrote: | What does the ` mean? | muststopmyths wrote: | That's the convention on windows for denoting 64-bit addresses, | separating the two 32bit parts with the backtick. Don't recall | why now. | avianlyric wrote: | I assume it just makes the address easier to read. I imagine | most programs don't deal with address spaces larger than 4GB, | so being able to quickly identify the lower bytes of the | address when physically looking at a memory address is | probably quite handy. ___________________________________________________________________ (page generated 2022-12-18 23:00 UTC)