Re: [Xen-devel] [PATCH v4 16/16] libxl/arm: Add the size of ACPI tables to maxmem

[Shannon Zhao <zhaoshenglong@xxxxxxxxxx>]

On 2016/8/30 3:07, Julien Grall wrote:
> Hi Shannon,
> 
> On 16/08/2016 06:25, Shannon Zhao wrote:
>> From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
>>
>> While it defines the maximum size of guest ACPI tables in guest
>> memory layout, here it adds the size to set the target maxmem
>> to avoid providing less available memory for guest.
>>
>> Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
>> ---
>>  tools/libxl/libxl_arm.c | 11 +++++++++++
>>  1 file changed, 11 insertions(+)
>>
>> diff --git a/tools/libxl/libxl_arm.c b/tools/libxl/libxl_arm.c
>> index d436167..75b2589 100644
>> --- a/tools/libxl/libxl_arm.c
>> +++ b/tools/libxl/libxl_arm.c
>> @@ -103,6 +103,17 @@ int libxl__arch_domain_save_config(libxl__gc *gc,
>>  int libxl__arch_domain_create(libxl__gc *gc, libxl_domain_config
>> *d_config,
>>                                uint32_t domid)
>>  {
>> +    libxl_domain_build_info *const info = &d_config->b_info;
>> +    libxl_ctx *ctx = libxl__gc_owner(gc);
>> +
>> +    /* Add the size of ACPI tables to maxmem if ACPI is enabled for
>> guest. */
>> +    if (libxl_defbool_val(info->acpi) &&
>> +        xc_domain_setmaxmem(ctx->xch, domid, info->target_memkb +
>> +        LIBXL_MAXMEM_CONSTANT + GUEST_ACPI_SIZE / 1024) < 0) {
> 
> Why can't we use the estimate size here? It would be better than
> increasing by a constant again the max size (I doubt the ACPI tables
> will be 2MB every time).
> 
The estimate action happens after libxl__arch_domain_create(), I think.
So it can't get the estimate size here.

Also, it's better to add the max size so that it doesn't have to change
here when it adds other contents to the ACPI tables.

Thanks,
-- 
Shannon


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