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Re: [Xen-devel] [PATCH v2] console: increase initial conring size

>>> On 05.12.14 at 16:50, <daniel.kiper@xxxxxxxxxx> wrote:
> In general initial conring size is sufficient. However, if log
> level is increased on platforms which have e.g. huge number
> of memory regions (I have an IBM System x3550 M2 with 8 GiB RAM
> which has more than 200 entries in EFI memory map) then some
> of earlier messages in console ring are overwritten. It means
> that in case of issues deeper analysis can be hindered. Sadly
> conring_size argument does not help because new console buffer
> is allocated late on heap. It means that it is not possible to
> allocate larger ring earlier. So, in this situation initial
> conring size should be increased. My experiments showed that
> even on not so big machines more than 26 KiB of free space are
> needed for initial messages. In theory we could increase conring
> size buffer to 32 KiB. However, I think that this value could be
> too small for huge machines with large number of ACPI tables and
> EFI memory regions. Hence, this patch increases initial conring
> size to 64 KiB.
> Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>

Actually meanwhile I spotted a (minor) downside to this approach:
It raises the lower limit of the permanent ring size to 64k too.


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