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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH] xen/arm: Sanity test specified domain's memory for being a multiple of a page size
On 09-Oct-26 10:27, Alejandro Vallejo wrote: > On Wed Oct 7, 2026 at 4:31 PM CEST, Orzel, Michal wrote: >> >> >> On 07-Oct-26 16:21, Alejandro Vallejo wrote: >>> On Wed Oct 7, 2026 at 4:11 PM CEST, Orzel, Michal wrote: >>>> >>>> >>>> On 07-Oct-26 15:40, Alejandro Vallejo wrote: >>>>> On Wed Oct 7, 2026 at 2:48 PM CEST, Michal Orzel wrote: >>>>>> We require memory to allocate for a domain as RAM to be a multiple of a >>>>>> page size. However, we neither document this nor sanity test. Specifying >>>>>> memory size that does not conform to this requirement fails the domain >>>>>> memory allocation in the non-obvious way that is difficult to parse for >>>>>> the user (printing over-allocation messages followed by the panic that >>>>>> Xen >>>>>> could not allocate the requested amount of memory). >>>>>> >>>>>> While there, fix indentation from tabs to spaces for "memory" parameter >>>>>> in >>>>>> booting.txt. >>>>>> >>>>>> Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx> >>>>>> --- >>>>>> docs/misc/arm/device-tree/booting.txt | 4 ++-- >>>>>> docs/misc/xen-command-line.pandoc | 5 +++-- >>>>>> xen/arch/arm/domain_build.c | 6 ++++++ >>>>>> xen/common/device-tree/dom0less-build.c | 7 +++++++ >>>>>> 4 files changed, 18 insertions(+), 4 deletions(-) >>>>>> >>>>>> diff --git a/docs/misc/arm/device-tree/booting.txt >>>>>> b/docs/misc/arm/device-tree/booting.txt >>>>>> index bcb06bc796bf..7dfac2062a37 100644 >>>>>> --- a/docs/misc/arm/device-tree/booting.txt >>>>>> +++ b/docs/misc/arm/device-tree/booting.txt >>>>>> @@ -155,8 +155,8 @@ with the following properties: >>>>>> >>>>>> - memory >>>>>> >>>>>> - A 64-bit integer specifying the amount of kilobytes of RAM to >>>>>> - allocate to the guest. >>>>>> + A 64-bit integer specifying the amount of kilobytes of RAM to >>>>>> + allocate to the guest. Must be a multiple of 4KB (the page size). >>>>> >>>>> nit: s/KB/KiB >>>> Is it? I don't think it matters at all seeing the number of occurrences in >>>> the code. >>>> >>>>> >>>>> But page size isn't always 4KiB on all ports. PowerPC has 64KiB pages. >>>>> IMO, 4KB shouldn't be here or elsewhere in documentation. >>>> This is Arm doc and on Arm we only support 4KB at the moment. User should >>>> not >>>> need to dig into the code to check what is the page size. It's better imo >>>> to >>>> give this information right away and change in the future when we add >>>> support >>>> for 16 and 64KB pages on Arm. >>> >>> This is already the only reference the other ports have for dom0less. >>> The document shouldn't be here since the movement of dom0less to common >>> code, but the side effect of it is that this no longer an arm-only >>> reference. >>> >>> I won't be annoying about moving the doc on this patch because that's a >>> separate matter, but not adding more easily avoidable debt seems >>> warranted. >> I don't quite understand your reasoning. If you worry about dom0less != Arm, >> then on that basis HAS_DOM0LESS is selected only for Arm and RISCV where >> PAGE_SIZE is 4KB. I don't think I'm introducing any doubt here. I can remove >> the >> 4KB mentioning from the docs if you really insist but at least for me it's >> clearer for the user to know right away what's the requirement for the size. > > It's a small adjustment to make the documentation truly generic. And > prevents the pgsz == 4KiB assumption from spreading further. Many docs > are spawned from copying other docs. > > If you're so strongly against, that's fine; it's not incorrect today. > I still think the 4K should be gone, but if don't want to block the > patch on such silly things. Fine, I'll remove 4KB mentioning from the docs. > > Reviewed-by: Alejandro Vallejo <alejandro.garciavallejo@xxxxxxx> Thanks. I'll handle the changes on commit. ~Michal
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