From: Thomas Gleixner <tglx@linutronix.de>
To: Saurabh Singh Sengar <ssengar@linux.microsoft.com>,
"H. Peter Anvin" <hpa@zytor.com>
Cc: mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
x86@kernel.org, johan+linaro@kernel.org,
isaku.yamahata@intel.com, mikelley@microsoft.com,
linux-kernel@vger.kernel.org, andriy.shevchenko@intel.com
Subject: Re: [PATCH v2] x86/ioapic: Don't return 0 from arch_dynirq_lower_bound()
Date: Wed, 12 Apr 2023 17:37:27 +0200 [thread overview]
Message-ID: <87v8i1yuvc.ffs@tglx> (raw)
In-Reply-To: <20230328144834.GA17868@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net>
On Tue, Mar 28 2023 at 07:48, Saurabh Singh Sengar wrote:
> On Tue, Mar 28, 2023 at 06:59:04AM -0700, H. Peter Anvin wrote:
>>
>> Is there any reason why this variable can't be initialized to a fixed nonzero number, like 16?
>
> Yes, initializing gst_top to any non-zero value should fix this issue.
> At first I thought to intialize gst_top to 1.
That works only in your case. Some boot time registrations of IO_APICs
use gsi_top as the base. So initializing gsi_top to N would move IOAPIC[0]
interrupts out to irq N... and make the legacy interrupts fail.
That whole IOAPIC registration could do with some major cleanup, but
that's a different story.
Thanks,
tglx
next prev parent reply other threads:[~2023-04-12 15:37 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-28 7:30 [PATCH v2] x86/ioapic: Don't return 0 from arch_dynirq_lower_bound() Saurabh Sengar
2023-03-28 13:59 ` H. Peter Anvin
2023-03-28 14:48 ` Saurabh Singh Sengar
2023-04-12 15:37 ` Thomas Gleixner [this message]
2023-04-11 6:09 ` Saurabh Singh Sengar
2023-04-12 15:55 ` [tip: x86/apic] " tip-bot2 for Saurabh Sengar
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