Hi, As I had issues with some hardware needing the acpi=off xen command line switch to work properly (at least it seems so) with the xen kernel, at the same time using acpi=off was discouraged, this doesn''t get out of my head. I also see that this is a often-repeated issue in the mailing list, but all I read about it didn''t enlighten me, so I come back with my questions: - why exactly am I not supposed to use acpi=off? - what can/will happen when I do so? - does the discouragement of acpi=off absolutely "forbid" me to use it in stable production environments, or is it just "not optimal" to do it, but acceptable if there''s no other (easy) way to get some hardware running with xen and there''s not enough money to buy as much hardware until I have some which does the acpi stuff well with xen? Thanks in advance Henning _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi, I repost this because I believe that somebody here knows an answer for that question, and I am not the only one with such problems. I get those problems now also at home, where I can''t spend money on hardware until I find working hardware by accident, and the hardware posted as known to work is also over my budget - so I like to use that machine with acpi=off, but I want to know what the consequences can be. Please also let me know if I do something wrong in the style I post my questions - I made sure that I read the available docs, and searched the mailing list, but didn''t find helpful answers. Thank you very much in advance. Henning On Sat, 2006-01-14 at 20:46 +0100, Henning Sprang wrote:> Hi, > As I had issues with some hardware needing the acpi=off xen command line > switch to work properly (at least it seems so) with the xen kernel, at > the same time using acpi=off was discouraged, this doesn''t get out of my > head. > I also see that this is a often-repeated issue in the mailing list, but > all I read about it didn''t enlighten me, so I come back with my > questions: > > - why exactly am I not supposed to use acpi=off? > > - what can/will happen when I do so? > > - does the discouragement of acpi=off absolutely "forbid" me to use it > in stable production environments, or is it just "not optimal" to do it, > but acceptable if there''s no other (easy) way to get some hardware > running with xen and there''s not enough money to buy as much hardware > until I have some which does the acpi stuff well with xen? > > > Thanks in advance > Henning > > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
I''m not exactly a specialist on PC hardware, but here my try at an explanation: ACPI is basically a way for the hardware to tell the OS how it works, the BIOS provides tables with information about what resources are available, how they''re wired together, etc. Unfortunately, lots of mainboard vendors don''t care much about the "quality" of their tables, even if they''re plainly wrong, they count as "good enough" if the windows HAL parses them into something usable. acpi=off tells xen and/or the kernel to ignore those tables. Instead, it tries to "guess" what is there by using PNP bios, PCI-pnp, and assuming the board is PC-XT compatible. if those guesses are correct for the functions you need to use, you won''t need acpi. Now, as a side effect, the APIC (Advanced programmable interrupt controller) won''t be found without ACPI, so unless there''s a way to force APIC use without ACPI, you''ll loose the APIC features, meaning you''ll have to live with the old PC-XT interrupt features (two pics with 8 IRQ-Lines each, cascaded on IRQ2) Now if your hardware has special interrupt needs and you don''t mind several devices sharing the same IRQ, you won''t need APIC. Still, my advice would be to try to get acpi working, upgrading to a current BIOS version often helps. /Ernst On Friday 20 January 2006 11:17, Henning Sprang wrote: ...> I get those problems now also at home, where I can''t spend money on > hardware until I find working hardware by accident, and the hardware > posted as known to work is also over my budget - so I like to use that > machine with acpi=off, but I want to know what the consequences can be....> > - why exactly am I not supposed to use acpi=off? > > > > - what can/will happen when I do so? > > > > - does the discouragement of acpi=off absolutely "forbid" me to use it > > in stable production environments, or is it just "not optimal" to do it, > > but acceptable if there''s no other (easy) way to get some hardware > > running with xen and there''s not enough money to buy as much hardware > > until I have some which does the acpi stuff well with xen?_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users